Rename Python 3 markdown files into 'python'

```
for f in $(find . -iname "*python3*" | grep -vE 'git'); do
  fnew=$(echo "$f" | sed 's/python3/python/')
  git mv "$f" "$fnew"
done

1 files changed, 1042 insertions, 0 deletions

diff --git a/python.html.markdown b/python.html.markdown
new file mode 100644
index 00000000..f69ffb14
--- /dev/null
+++ b/python.html.markdown
@@ -0,0 +1,1042 @@
+---
+language: python3
+contributors:
+    - ["Louie Dinh", "http://pythonpracticeprojects.com"]
+    - ["Steven Basart", "http://github.com/xksteven"]
+    - ["Andre Polykanine", "https://github.com/Oire"]
+    - ["Zachary Ferguson", "http://github.com/zfergus2"]
+    - ["evuez", "http://github.com/evuez"]
+    - ["Rommel Martinez", "https://ebzzry.io"]
+    - ["Roberto Fernandez Diaz", "https://github.com/robertofd1995"]
+    - ["caminsha", "https://github.com/caminsha"]
+filename: learnpython3.py
+---
+
+Python was created by Guido van Rossum in the early 90s. It is now one of the most popular
+languages in existence. I fell in love with Python for its syntactic clarity. It's basically
+executable pseudocode.
+
+Note: This article applies to Python 3 specifically. Check out [here](http://learnxinyminutes.com/docs/python/) if you want to learn the old Python 2.7
+
+```python
+
+# Single line comments start with a number symbol.
+
+""" Multiline strings can be written
+    using three "s, and are often used
+    as documentation.
+"""
+
+####################################################
+## 1. Primitive Datatypes and Operators
+####################################################
+
+# You have numbers
+3  # => 3
+
+# Math is what you would expect
+1 + 1   # => 2
+8 - 1   # => 7
+10 * 2  # => 20
+35 / 5  # => 7.0
+
+# Integer division rounds down for both positive and negative numbers.
+5 // 3       # => 1
+-5 // 3      # => -2
+5.0 // 3.0   # => 1.0 # works on floats too
+-5.0 // 3.0  # => -2.0
+
+# The result of division is always a float
+10.0 / 3  # => 3.3333333333333335
+
+# Modulo operation
+7 % 3  # => 1
+
+# Exponentiation (x**y, x to the yth power)
+2**3  # => 8
+
+# Enforce precedence with parentheses
+1 + 3 * 2  # => 7
+(1 + 3) * 2  # => 8
+
+# Boolean values are primitives (Note: the capitalization)
+True  # => True
+False  # => False
+
+# negate with not
+not True   # => False
+not False  # => True
+
+# Boolean Operators
+# Note "and" and "or" are case-sensitive
+True and False  # => False
+False or True   # => True
+
+# True and False are actually 1 and 0 but with different keywords
+True + True # => 2
+True * 8    # => 8
+False - 5   # => -5
+
+# Comparison operators look at the numerical value of True and False
+0 == False  # => True
+1 == True   # => True
+2 == True   # => False
+-5 != False # => True
+
+# Using boolean logical operators on ints casts them to booleans for evaluation, but their non-cast value is returned
+# Don't mix up with bool(ints) and bitwise and/or (&,|)
+bool(0)     # => False
+bool(4)     # => True
+bool(-6)    # => True
+0 and 2     # => 0
+-5 or 0     # => -5
+
+# Equality is ==
+1 == 1  # => True
+2 == 1  # => False
+
+# Inequality is !=
+1 != 1  # => False
+2 != 1  # => True
+
+# More comparisons
+1 < 10  # => True
+1 > 10  # => False
+2 <= 2  # => True
+2 >= 2  # => True
+
+# Seeing whether a value is in a range
+1 < 2 and 2 < 3  # => True
+2 < 3 and 3 < 2  # => False
+# Chaining makes this look nicer
+1 < 2 < 3  # => True
+2 < 3 < 2  # => False
+
+# (is vs. ==) is checks if two variables refer to the same object, but == checks
+# if the objects pointed to have the same values.
+a = [1, 2, 3, 4]  # Point a at a new list, [1, 2, 3, 4]
+b = a             # Point b at what a is pointing to
+b is a            # => True, a and b refer to the same object
+b == a            # => True, a's and b's objects are equal
+b = [1, 2, 3, 4]  # Point b at a new list, [1, 2, 3, 4]
+b is a            # => False, a and b do not refer to the same object
+b == a            # => True, a's and b's objects are equal
+
+# Strings are created with " or '
+"This is a string."
+'This is also a string.'
+
+# Strings can be added too! But try not to do this.
+"Hello " + "world!"  # => "Hello world!"
+# String literals (but not variables) can be concatenated without using '+'
+"Hello " "world!"    # => "Hello world!"
+
+# A string can be treated like a list of characters
+"This is a string"[0]  # => 'T'
+
+# You can find the length of a string
+len("This is a string")  # => 16
+
+# You can also format using f-strings or formatted string literals (in Python 3.6+)
+name = "Reiko"
+f"She said her name is {name}." # => "She said her name is Reiko"
+# You can basically put any Python statement inside the braces and it will be output in the string.
+f"{name} is {len(name)} characters long." # => "Reiko is 5 characters long."
+
+
+# None is an object
+None  # => None
+
+# Don't use the equality "==" symbol to compare objects to None
+# Use "is" instead. This checks for equality of object identity.
+"etc" is None  # => False
+None is None   # => True
+
+# None, 0, and empty strings/lists/dicts/tuples all evaluate to False.
+# All other values are True
+bool(0)   # => False
+bool("")  # => False
+bool([])  # => False
+bool({})  # => False
+bool(())  # => False
+
+####################################################
+## 2. Variables and Collections
+####################################################
+
+# Python has a print function
+print("I'm Python. Nice to meet you!")  # => I'm Python. Nice to meet you!
+
+# By default the print function also prints out a newline at the end.
+# Use the optional argument end to change the end string.
+print("Hello, World", end="!")  # => Hello, World!
+
+# Simple way to get input data from console
+input_string_var = input("Enter some data: ") # Returns the data as a string
+# Note: In earlier versions of Python, input() method was named as raw_input()
+
+# There are no declarations, only assignments.
+# Convention is to use lower_case_with_underscores
+some_var = 5
+some_var  # => 5
+
+# Accessing a previously unassigned variable is an exception.
+# See Control Flow to learn more about exception handling.
+some_unknown_var  # Raises a NameError
+
+# if can be used as an expression
+# Equivalent of C's '?:' ternary operator
+"yahoo!" if 3 > 2 else 2  # => "yahoo!"
+
+# Lists store sequences
+li = []
+# You can start with a prefilled list
+other_li = [4, 5, 6]
+
+# Add stuff to the end of a list with append
+li.append(1)    # li is now [1]
+li.append(2)    # li is now [1, 2]
+li.append(4)    # li is now [1, 2, 4]
+li.append(3)    # li is now [1, 2, 4, 3]
+# Remove from the end with pop
+li.pop()        # => 3 and li is now [1, 2, 4]
+# Let's put it back
+li.append(3)    # li is now [1, 2, 4, 3] again.
+
+# Access a list like you would any array
+li[0]   # => 1
+# Look at the last element
+li[-1]  # => 3
+
+# Looking out of bounds is an IndexError
+li[4]  # Raises an IndexError
+
+# You can look at ranges with slice syntax.
+# The start index is included, the end index is not
+# (It's a closed/open range for you mathy types.)
+li[1:3]   # Return list from index 1 to 3 => [2, 4]
+li[2:]    # Return list starting from index 2 => [4, 3]
+li[:3]    # Return list from beginning until index 3  => [1, 2, 4]
+li[::2]   # Return list selecting every second entry => [1, 4]
+li[::-1]  # Return list in reverse order => [3, 4, 2, 1]
+# Use any combination of these to make advanced slices
+# li[start:end:step]
+
+# Make a one layer deep copy using slices
+li2 = li[:]  # => li2 = [1, 2, 4, 3] but (li2 is li) will result in false.
+
+# Remove arbitrary elements from a list with "del"
+del li[2]  # li is now [1, 2, 3]
+
+# Remove first occurrence of a value
+li.remove(2)  # li is now [1, 3]
+li.remove(2)  # Raises a ValueError as 2 is not in the list
+
+# Insert an element at a specific index
+li.insert(1, 2)  # li is now [1, 2, 3] again
+
+# Get the index of the first item found matching the argument
+li.index(2)  # => 1
+li.index(4)  # Raises a ValueError as 4 is not in the list
+
+# You can add lists
+# Note: values for li and for other_li are not modified.
+li + other_li  # => [1, 2, 3, 4, 5, 6]
+
+# Concatenate lists with "extend()"
+li.extend(other_li)  # Now li is [1, 2, 3, 4, 5, 6]
+
+# Check for existence in a list with "in"
+1 in li  # => True
+
+# Examine the length with "len()"
+len(li)  # => 6
+
+
+# Tuples are like lists but are immutable.
+tup = (1, 2, 3)
+tup[0]      # => 1
+tup[0] = 3  # Raises a TypeError
+
+# Note that a tuple of length one has to have a comma after the last element but
+# tuples of other lengths, even zero, do not.
+type((1))   # => <class 'int'>
+type((1,))  # => <class 'tuple'>
+type(())    # => <class 'tuple'>
+
+# You can do most of the list operations on tuples too
+len(tup)         # => 3
+tup + (4, 5, 6)  # => (1, 2, 3, 4, 5, 6)
+tup[:2]          # => (1, 2)
+2 in tup         # => True
+
+# You can unpack tuples (or lists) into variables
+a, b, c = (1, 2, 3)  # a is now 1, b is now 2 and c is now 3
+# You can also do extended unpacking
+a, *b, c = (1, 2, 3, 4)  # a is now 1, b is now [2, 3] and c is now 4
+# Tuples are created by default if you leave out the parentheses
+d, e, f = 4, 5, 6  # tuple 4, 5, 6 is unpacked into variables d, e and f
+# respectively such that d = 4, e = 5 and f = 6
+# Now look how easy it is to swap two values
+e, d = d, e  # d is now 5 and e is now 4
+
+
+# Dictionaries store mappings from keys to values
+empty_dict = {}
+# Here is a prefilled dictionary
+filled_dict = {"one": 1, "two": 2, "three": 3}
+
+# Note keys for dictionaries have to be immutable types. This is to ensure that
+# the key can be converted to a constant hash value for quick look-ups.
+# Immutable types include ints, floats, strings, tuples.
+invalid_dict = {[1,2,3]: "123"}  # => Raises a TypeError: unhashable type: 'list'
+valid_dict = {(1,2,3):[1,2,3]}   # Values can be of any type, however.
+
+# Look up values with []
+filled_dict["one"]  # => 1
+
+# Get all keys as an iterable with "keys()". We need to wrap the call in list()
+# to turn it into a list. We'll talk about those later.  Note - for Python
+# versions <3.7, dictionary key ordering is not guaranteed. Your results might
+# not match the example below exactly. However, as of Python 3.7, dictionary
+# items maintain the order at which they are inserted into the dictionary.
+list(filled_dict.keys())  # => ["three", "two", "one"] in Python <3.7
+list(filled_dict.keys())  # => ["one", "two", "three"] in Python 3.7+
+
+
+# Get all values as an iterable with "values()". Once again we need to wrap it
+# in list() to get it out of the iterable. Note - Same as above regarding key
+# ordering.
+list(filled_dict.values())  # => [3, 2, 1]  in Python <3.7
+list(filled_dict.values())  # => [1, 2, 3] in Python 3.7+
+
+# Check for existence of keys in a dictionary with "in"
+"one" in filled_dict  # => True
+1 in filled_dict      # => False
+
+# Looking up a non-existing key is a KeyError
+filled_dict["four"]  # KeyError
+
+# Use "get()" method to avoid the KeyError
+filled_dict.get("one")      # => 1
+filled_dict.get("four")     # => None
+# The get method supports a default argument when the value is missing
+filled_dict.get("one", 4)   # => 1
+filled_dict.get("four", 4)  # => 4
+
+# "setdefault()" inserts into a dictionary only if the given key isn't present
+filled_dict.setdefault("five", 5)  # filled_dict["five"] is set to 5
+filled_dict.setdefault("five", 6)  # filled_dict["five"] is still 5
+
+# Adding to a dictionary
+filled_dict.update({"four":4})  # => {"one": 1, "two": 2, "three": 3, "four": 4}
+filled_dict["four"] = 4         # another way to add to dict
+
+# Remove keys from a dictionary with del
+del filled_dict["one"]  # Removes the key "one" from filled dict
+
+# From Python 3.5 you can also use the additional unpacking options
+{'a': 1, **{'b': 2}}  # => {'a': 1, 'b': 2}
+{'a': 1, **{'a': 2}}  # => {'a': 2}
+
+
+
+# Sets store ... well sets
+empty_set = set()
+# Initialize a set with a bunch of values. Yeah, it looks a bit like a dict. Sorry.
+some_set = {1, 1, 2, 2, 3, 4}  # some_set is now {1, 2, 3, 4}
+
+# Similar to keys of a dictionary, elements of a set have to be immutable.
+invalid_set = {[1], 1}  # => Raises a TypeError: unhashable type: 'list'
+valid_set = {(1,), 1}
+
+# Add one more item to the set
+filled_set = some_set
+filled_set.add(5)  # filled_set is now {1, 2, 3, 4, 5}
+# Sets do not have duplicate elements
+filled_set.add(5)  # it remains as before {1, 2, 3, 4, 5}
+
+# Do set intersection with &
+other_set = {3, 4, 5, 6}
+filled_set & other_set  # => {3, 4, 5}
+
+# Do set union with |
+filled_set | other_set  # => {1, 2, 3, 4, 5, 6}
+
+# Do set difference with -
+{1, 2, 3, 4} - {2, 3, 5}  # => {1, 4}
+
+# Do set symmetric difference with ^
+{1, 2, 3, 4} ^ {2, 3, 5}  # => {1, 4, 5}
+
+# Check if set on the left is a superset of set on the right
+{1, 2} >= {1, 2, 3} # => False
+
+# Check if set on the left is a subset of set on the right
+{1, 2} <= {1, 2, 3} # => True
+
+# Check for existence in a set with in
+2 in filled_set   # => True
+10 in filled_set  # => False
+
+# Make a one layer deep copy
+filled_set = some_set.copy()  # filled_set is {1, 2, 3, 4, 5}
+filled_set is some_set        # => False
+
+
+####################################################
+## 3. Control Flow and Iterables
+####################################################
+
+# Let's just make a variable
+some_var = 5
+
+# Here is an if statement. Indentation is significant in Python!
+# Convention is to use four spaces, not tabs.
+# This prints "some_var is smaller than 10"
+if some_var > 10:
+    print("some_var is totally bigger than 10.")
+elif some_var < 10:    # This elif clause is optional.
+    print("some_var is smaller than 10.")
+else:                  # This is optional too.
+    print("some_var is indeed 10.")
+
+
+"""
+For loops iterate over lists
+prints:
+    dog is a mammal
+    cat is a mammal
+    mouse is a mammal
+"""
+for animal in ["dog", "cat", "mouse"]:
+    # You can use format() to interpolate formatted strings
+    print("{} is a mammal".format(animal))
+
+"""
+"range(number)" returns an iterable of numbers
+from zero to the given number
+prints:
+    0
+    1
+    2
+    3
+"""
+for i in range(4):
+    print(i)
+
+"""
+"range(lower, upper)" returns an iterable of numbers
+from the lower number to the upper number
+prints:
+    4
+    5
+    6
+    7
+"""
+for i in range(4, 8):
+    print(i)
+
+"""
+"range(lower, upper, step)" returns an iterable of numbers
+from the lower number to the upper number, while incrementing
+by step. If step is not indicated, the default value is 1.
+prints:
+    4
+    6
+"""
+for i in range(4, 8, 2):
+    print(i)
+
+"""
+To loop over a list, and retrieve both the index and the value of each item in the list
+prints:
+    0 dog
+    1 cat
+    2 mouse
+"""
+animals = ["dog", "cat", "mouse"]
+for i, value in enumerate(animals):
+    print(i, value)
+
+"""
+While loops go until a condition is no longer met.
+prints:
+    0
+    1
+    2
+    3
+"""
+x = 0
+while x < 4:
+    print(x)
+    x += 1  # Shorthand for x = x + 1
+
+# Handle exceptions with a try/except block
+try:
+    # Use "raise" to raise an error
+    raise IndexError("This is an index error")
+except IndexError as e:
+    pass                 # Pass is just a no-op. Usually you would do recovery here.
+except (TypeError, NameError):
+    pass                 # Multiple exceptions can be handled together, if required.
+else:                    # Optional clause to the try/except block. Must follow all except blocks
+    print("All good!")   # Runs only if the code in try raises no exceptions
+finally:                 #  Execute under all circumstances
+    print("We can clean up resources here")
+
+# Instead of try/finally to cleanup resources you can use a with statement
+with open("myfile.txt") as f:
+    for line in f:
+        print(line)
+
+# Writing to a file
+contents = {"aa": 12, "bb": 21}
+with open("myfile1.txt", "w+") as file:
+    file.write(str(contents))        # writes a string to a file
+
+with open("myfile2.txt", "w+") as file:
+    file.write(json.dumps(contents)) # writes an object to a file
+
+# Reading from a file
+with open('myfile1.txt', "r+") as file:
+    contents = file.read()           # reads a string from a file
+print(contents)
+# print: {"aa": 12, "bb": 21}
+
+with open('myfile2.txt', "r+") as file:
+    contents = json.load(file)       # reads a json object from a file
+print(contents)     
+# print: {"aa": 12, "bb": 21}
+
+
+# Python offers a fundamental abstraction called the Iterable.
+# An iterable is an object that can be treated as a sequence.
+# The object returned by the range function, is an iterable.
+
+filled_dict = {"one": 1, "two": 2, "three": 3}
+our_iterable = filled_dict.keys()
+print(our_iterable)  # => dict_keys(['one', 'two', 'three']). This is an object that implements our Iterable interface.
+
+# We can loop over it.
+for i in our_iterable:
+    print(i)  # Prints one, two, three
+
+# However we cannot address elements by index.
+our_iterable[1]  # Raises a TypeError
+
+# An iterable is an object that knows how to create an iterator.
+our_iterator = iter(our_iterable)
+
+# Our iterator is an object that can remember the state as we traverse through it.
+# We get the next object with "next()".
+next(our_iterator)  # => "one"
+
+# It maintains state as we iterate.
+next(our_iterator)  # => "two"
+next(our_iterator)  # => "three"
+
+# After the iterator has returned all of its data, it raises a StopIteration exception
+next(our_iterator)  # Raises StopIteration
+
+# We can also loop over it, in fact, "for" does this implicitly!
+our_iterator = iter(our_iterable)
+for i in our_iterator:
+    print(i)  # Prints one, two, three
+
+# You can grab all the elements of an iterable or iterator by calling list() on it.
+list(our_iterable)  # => Returns ["one", "two", "three"]
+list(our_iterator)  # => Returns [] because state is saved
+
+
+####################################################
+## 4. Functions
+####################################################
+
+# Use "def" to create new functions
+def add(x, y):
+    print("x is {} and y is {}".format(x, y))
+    return x + y  # Return values with a return statement
+
+# Calling functions with parameters
+add(5, 6)  # => prints out "x is 5 and y is 6" and returns 11
+
+# Another way to call functions is with keyword arguments
+add(y=6, x=5)  # Keyword arguments can arrive in any order.
+
+# You can define functions that take a variable number of
+# positional arguments
+def varargs(*args):
+    return args
+
+varargs(1, 2, 3)  # => (1, 2, 3)
+
+# You can define functions that take a variable number of
+# keyword arguments, as well
+def keyword_args(**kwargs):
+    return kwargs
+
+# Let's call it to see what happens
+keyword_args(big="foot", loch="ness")  # => {"big": "foot", "loch": "ness"}
+
+
+# You can do both at once, if you like
+def all_the_args(*args, **kwargs):
+    print(args)
+    print(kwargs)
+"""
+all_the_args(1, 2, a=3, b=4) prints:
+    (1, 2)
+    {"a": 3, "b": 4}
+"""
+
+# When calling functions, you can do the opposite of args/kwargs!
+# Use * to expand tuples and use ** to expand kwargs.
+args = (1, 2, 3, 4)
+kwargs = {"a": 3, "b": 4}
+all_the_args(*args)            # equivalent to all_the_args(1, 2, 3, 4)
+all_the_args(**kwargs)         # equivalent to all_the_args(a=3, b=4)
+all_the_args(*args, **kwargs)  # equivalent to all_the_args(1, 2, 3, 4, a=3, b=4)
+
+# Returning multiple values (with tuple assignments)
+def swap(x, y):
+    return y, x  # Return multiple values as a tuple without the parenthesis.
+                 # (Note: parenthesis have been excluded but can be included)
+
+x = 1
+y = 2
+x, y = swap(x, y)     # => x = 2, y = 1
+# (x, y) = swap(x,y)  # Again parenthesis have been excluded but can be included.
+
+# Function Scope
+x = 5
+
+def set_x(num):
+    # Local var x not the same as global variable x
+    x = num    # => 43
+    print(x)   # => 43
+
+def set_global_x(num):
+    global x
+    print(x)   # => 5
+    x = num    # global var x is now set to 6
+    print(x)   # => 6
+
+set_x(43)
+set_global_x(6)
+
+
+# Python has first class functions
+def create_adder(x):
+    def adder(y):
+        return x + y
+    return adder
+
+add_10 = create_adder(10)
+add_10(3)   # => 13
+
+# There are also anonymous functions
+(lambda x: x > 2)(3)                  # => True
+(lambda x, y: x ** 2 + y ** 2)(2, 1)  # => 5
+
+# There are built-in higher order functions
+list(map(add_10, [1, 2, 3]))          # => [11, 12, 13]
+list(map(max, [1, 2, 3], [4, 2, 1]))  # => [4, 2, 3]
+
+list(filter(lambda x: x > 5, [3, 4, 5, 6, 7]))  # => [6, 7]
+
+# We can use list comprehensions for nice maps and filters
+# List comprehension stores the output as a list which can itself be a nested list
+[add_10(i) for i in [1, 2, 3]]         # => [11, 12, 13]
+[x for x in [3, 4, 5, 6, 7] if x > 5]  # => [6, 7]
+
+# You can construct set and dict comprehensions as well.
+{x for x in 'abcddeef' if x not in 'abc'}  # => {'d', 'e', 'f'}
+{x: x**2 for x in range(5)}  # => {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
+
+
+####################################################
+## 5. Modules
+####################################################
+
+# You can import modules
+import math
+print(math.sqrt(16))  # => 4.0
+
+# You can get specific functions from a module
+from math import ceil, floor
+print(ceil(3.7))   # => 4.0
+print(floor(3.7))  # => 3.0
+
+# You can import all functions from a module.
+# Warning: this is not recommended
+from math import *
+
+# You can shorten module names
+import math as m
+math.sqrt(16) == m.sqrt(16)  # => True
+
+# Python modules are just ordinary Python files. You
+# can write your own, and import them. The name of the
+# module is the same as the name of the file.
+
+# You can find out which functions and attributes
+# are defined in a module.
+import math
+dir(math)
+
+# If you have a Python script named math.py in the same
+# folder as your current script, the file math.py will
+# be loaded instead of the built-in Python module.
+# This happens because the local folder has priority
+# over Python's built-in libraries.
+
+
+####################################################
+## 6. Classes
+####################################################
+
+# We use the "class" statement to create a class
+class Human:
+
+    # A class attribute. It is shared by all instances of this class
+    species = "H. sapiens"
+
+    # Basic initializer, this is called when this class is instantiated.
+    # Note that the double leading and trailing underscores denote objects
+    # or attributes that are used by Python but that live in user-controlled
+    # namespaces. Methods(or objects or attributes) like: __init__, __str__,
+    # __repr__ etc. are called special methods (or sometimes called dunder methods)
+    # You should not invent such names on your own.
+    def __init__(self, name):
+        # Assign the argument to the instance's name attribute
+        self.name = name
+
+        # Initialize property
+        self._age = 0
+
+    # An instance method. All methods take "self" as the first argument
+    def say(self, msg):
+        print("{name}: {message}".format(name=self.name, message=msg))
+
+    # Another instance method
+    def sing(self):
+        return 'yo... yo... microphone check... one two... one two...'
+
+    # A class method is shared among all instances
+    # They are called with the calling class as the first argument
+    @classmethod
+    def get_species(cls):
+        return cls.species
+
+    # A static method is called without a class or instance reference
+    @staticmethod
+    def grunt():
+        return "*grunt*"
+
+    # A property is just like a getter.
+    # It turns the method age() into an read-only attribute of the same name.
+    # There's no need to write trivial getters and setters in Python, though.
+    @property
+    def age(self):
+        return self._age
+
+    # This allows the property to be set
+    @age.setter
+    def age(self, age):
+        self._age = age
+
+    # This allows the property to be deleted
+    @age.deleter
+    def age(self):
+        del self._age
+
+
+# When a Python interpreter reads a source file it executes all its code.
+# This __name__ check makes sure this code block is only executed when this
+# module is the main program.
+if __name__ == '__main__':
+    # Instantiate a class
+    i = Human(name="Ian")
+    i.say("hi")                     # "Ian: hi"
+    j = Human("Joel")
+    j.say("hello")                  # "Joel: hello"
+    # i and j are instances of type Human, or in other words: they are Human objects
+
+    # Call our class method
+    i.say(i.get_species())          # "Ian: H. sapiens"
+    # Change the shared attribute
+    Human.species = "H. neanderthalensis"
+    i.say(i.get_species())          # => "Ian: H. neanderthalensis"
+    j.say(j.get_species())          # => "Joel: H. neanderthalensis"
+
+    # Call the static method
+    print(Human.grunt())            # => "*grunt*"
+    
+    # Cannot call static method with instance of object 
+    # because i.grunt() will automatically put "self" (the object i) as an argument
+    print(i.grunt())                # => TypeError: grunt() takes 0 positional arguments but 1 was given
+                                    
+    # Update the property for this instance
+    i.age = 42
+    # Get the property
+    i.say(i.age)                    # => "Ian: 42"
+    j.say(j.age)                    # => "Joel: 0"
+    # Delete the property
+    del i.age
+    # i.age                         # => this would raise an AttributeError
+
+
+####################################################
+## 6.1 Inheritance
+####################################################
+
+# Inheritance allows new child classes to be defined that inherit methods and
+# variables from their parent class. 
+
+# Using the Human class defined above as the base or parent class, we can
+# define a child class, Superhero, which inherits the class variables like
+# "species", "name", and "age", as well as methods, like "sing" and "grunt"
+# from the Human class, but can also have its own unique properties.
+
+# To take advantage of modularization by file you could place the classes above in their own files,
+# say, human.py
+
+# To import functions from other files use the following format
+# from "filename-without-extension" import "function-or-class"
+
+from human import Human
+
+
+# Specify the parent class(es) as parameters to the class definition
+class Superhero(Human):
+
+    # If the child class should inherit all of the parent's definitions without
+    # any modifications, you can just use the "pass" keyword (and nothing else)
+    # but in this case it is commented out to allow for a unique child class:
+    # pass
+
+    # Child classes can override their parents' attributes
+    species = 'Superhuman'
+
+    # Children automatically inherit their parent class's constructor including
+    # its arguments, but can also define additional arguments or definitions
+    # and override its methods such as the class constructor.
+    # This constructor inherits the "name" argument from the "Human" class and
+    # adds the "superpower" and "movie" arguments:
+    def __init__(self, name, movie=False,
+                 superpowers=["super strength", "bulletproofing"]):
+
+        # add additional class attributes:
+        self.fictional = True
+        self.movie = movie
+        # be aware of mutable default values, since defaults are shared
+        self.superpowers = superpowers
+
+        # The "super" function lets you access the parent class's methods
+        # that are overridden by the child, in this case, the __init__ method.
+        # This calls the parent class constructor:
+        super().__init__(name)
+
+    # override the sing method
+    def sing(self):
+        return 'Dun, dun, DUN!'
+
+    # add an additional instance method
+    def boast(self):
+        for power in self.superpowers:
+            print("I wield the power of {pow}!".format(pow=power))
+
+
+if __name__ == '__main__':
+    sup = Superhero(name="Tick")
+
+    # Instance type checks
+    if isinstance(sup, Human):
+        print('I am human')
+    if type(sup) is Superhero:
+        print('I am a superhero')
+
+    # Get the Method Resolution search Order used by both getattr() and super()
+    # This attribute is dynamic and can be updated
+    print(Superhero.__mro__)    # => (<class '__main__.Superhero'>,
+                                # => <class 'human.Human'>, <class 'object'>)
+
+    # Calls parent method but uses its own class attribute
+    print(sup.get_species())    # => Superhuman
+
+    # Calls overridden method
+    print(sup.sing())           # => Dun, dun, DUN!
+
+    # Calls method from Human
+    sup.say('Spoon')            # => Tick: Spoon
+
+    # Call method that exists only in Superhero
+    sup.boast()                 # => I wield the power of super strength!
+                                # => I wield the power of bulletproofing!
+
+    # Inherited class attribute
+    sup.age = 31
+    print(sup.age)              # => 31
+
+    # Attribute that only exists within Superhero
+    print('Am I Oscar eligible? ' + str(sup.movie))
+
+####################################################
+## 6.2 Multiple Inheritance
+####################################################
+
+# Another class definition
+# bat.py
+class Bat:
+
+    species = 'Baty'
+
+    def __init__(self, can_fly=True):
+        self.fly = can_fly
+
+    # This class also has a say method
+    def say(self, msg):
+        msg = '... ... ...'
+        return msg
+
+    # And its own method as well
+    def sonar(self):
+        return '))) ... ((('
+
+if __name__ == '__main__':
+    b = Bat()
+    print(b.say('hello'))
+    print(b.fly)
+
+
+# And yet another class definition that inherits from Superhero and Bat
+# superhero.py
+from superhero import Superhero
+from bat import Bat
+
+# Define Batman as a child that inherits from both Superhero and Bat
+class Batman(Superhero, Bat):
+
+    def __init__(self, *args, **kwargs):
+        # Typically to inherit attributes you have to call super:
+        # super(Batman, self).__init__(*args, **kwargs)      
+        # However we are dealing with multiple inheritance here, and super()
+        # only works with the next base class in the MRO list.
+        # So instead we explicitly call __init__ for all ancestors.
+        # The use of *args and **kwargs allows for a clean way to pass arguments,
+        # with each parent "peeling a layer of the onion".
+        Superhero.__init__(self, 'anonymous', movie=True, 
+                           superpowers=['Wealthy'], *args, **kwargs)
+        Bat.__init__(self, *args, can_fly=False, **kwargs)
+        # override the value for the name attribute
+        self.name = 'Sad Affleck'
+
+    def sing(self):
+        return 'nan nan nan nan nan batman!'
+
+
+if __name__ == '__main__':
+    sup = Batman()
+
+    # Get the Method Resolution search Order used by both getattr() and super().
+    # This attribute is dynamic and can be updated
+    print(Batman.__mro__)       # => (<class '__main__.Batman'>, 
+                                # => <class 'superhero.Superhero'>, 
+                                # => <class 'human.Human'>, 
+                                # => <class 'bat.Bat'>, <class 'object'>)
+
+    # Calls parent method but uses its own class attribute
+    print(sup.get_species())    # => Superhuman
+
+    # Calls overridden method
+    print(sup.sing())           # => nan nan nan nan nan batman!
+
+    # Calls method from Human, because inheritance order matters
+    sup.say('I agree')          # => Sad Affleck: I agree
+
+    # Call method that exists only in 2nd ancestor
+    print(sup.sonar())          # => ))) ... (((
+
+    # Inherited class attribute
+    sup.age = 100
+    print(sup.age)              # => 100
+
+    # Inherited attribute from 2nd ancestor whose default value was overridden.
+    print('Can I fly? ' + str(sup.fly)) # => Can I fly? False
+
+
+
+####################################################
+## 7. Advanced
+####################################################
+
+# Generators help you make lazy code.
+def double_numbers(iterable):
+    for i in iterable:
+        yield i + i
+
+# Generators are memory-efficient because they only load the data needed to
+# process the next value in the iterable. This allows them to perform
+# operations on otherwise prohibitively large value ranges.
+# NOTE: `range` replaces `xrange` in Python 3.
+for i in double_numbers(range(1, 900000000)):  # `range` is a generator.
+    print(i)
+    if i >= 30:
+        break
+
+# Just as you can create a list comprehension, you can create generator
+# comprehensions as well.
+values = (-x for x in [1,2,3,4,5])
+for x in values:
+    print(x)  # prints -1 -2 -3 -4 -5 to console/terminal
+
+# You can also cast a generator comprehension directly to a list.
+values = (-x for x in [1,2,3,4,5])
+gen_to_list = list(values)
+print(gen_to_list)  # => [-1, -2, -3, -4, -5]
+
+
+# Decorators
+# In this example `beg` wraps `say`. If say_please is True then it
+# will change the returned message.
+from functools import wraps
+
+
+def beg(target_function):
+    @wraps(target_function)
+    def wrapper(*args, **kwargs):
+        msg, say_please = target_function(*args, **kwargs)
+        if say_please:
+            return "{} {}".format(msg, "Please! I am poor :(")
+        return msg
+
+    return wrapper
+
+
+@beg
+def say(say_please=False):
+    msg = "Can you buy me a beer?"
+    return msg, say_please
+
+
+print(say())                 # Can you buy me a beer?
+print(say(say_please=True))  # Can you buy me a beer? Please! I am poor :(
+```
+
+## Ready For More?
+
+### Free Online
+
+* [Automate the Boring Stuff with Python](https://automatetheboringstuff.com)
+* [Ideas for Python Projects](http://pythonpracticeprojects.com)
+* [The Official Docs](http://docs.python.org/3/)
+* [Hitchhiker's Guide to Python](http://docs.python-guide.org/en/latest/)
+* [Python Course](http://www.python-course.eu/index.php)
+* [First Steps With Python](https://realpython.com/learn/python-first-steps/)
+* [A curated list of awesome Python frameworks, libraries and software](https://github.com/vinta/awesome-python)
+* [30 Python Language Features and Tricks You May Not Know About](http://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html)
+* [Official Style Guide for Python](https://www.python.org/dev/peps/pep-0008/)
+* [Python 3 Computer Science Circles](http://cscircles.cemc.uwaterloo.ca/)
+* [Dive Into Python 3](http://www.diveintopython3.net/index.html)
+* [A Crash Course in Python for Scientists](http://nbviewer.jupyter.org/gist/anonymous/5924718)