1. Creating lists with list comprehensions

>>> feast = ['lambs', 'sloths', 'orangutans', 'breakfast cereals',
                        'fruit bats']

>>> comprehension = [delicacy.capitalize() for delicacy in feast]

2. Filtering lists with list comprehensions

>>> feast = ['spam', 'sloths', 'orangutans', 'breakfast cereals',
            'fruit bats']

>>> comprehension = [delicacy for delicacy in feast if len(delicacy) > 6]

3. Unpacking tuples in list comprehensions

>>> list_of_tuples = [(1, 'lumberjack'), (2, 'inquisition'), (4, 'spam')]

>>> comprehension = [ skit * number for number, skit in list_of_tuples ]

4. Double list comprehension

>>> list_of_eggs = ['poached egg', 'fried egg']

>>> list_of_meats = ['lite spam', 'ham spam', 'fried spam']

>>> comprehension = [ '{0} and {1}'.format(egg, meat) for egg in list_of_eggs for meat in list_of_meats]

5. Creating a set with set comprehension

>>> comprehension = { x for x in 'aabbbcccc'}

6. Creating a dictionary with dictionary comprehension

>>> dict_of_weapons = {'first': 'fear', 'second': 'surprise',
            'third':'ruthless efficiency', 'forth':'fanatical devotion',
            'fifth': None}

>>> dict_comprehension = { k.upper(): weapon for k, weapon in dict_of_weapons.iteritems() if weapon}

>>> 'first' in dict_comprehension
        ???

7. Count even numbers

This is from CodingBat "count_evens" (http://codingbat.com/prob/p189616)

Using list comprehension, return the number of even ints in the given array. Note: the % "mod" operator computes the remainder, e.g. 5 % 2 is 1.

count_evens([2, 1, 2, 3, 4]) → 3

count_evens([2, 2, 0]) → 3

count_evens([1, 3, 5]) → 0

def count_evens(nums):