List Comprehensions is a very powerful tool, which creates a new list based on another list, in a single, readable line.
For example, let's say we need to create a list of integers which specify the length of each word in a certain sentence, but only if the word is not the word "the".
sentence = "the quick brown fox jumps over the lazy dog" words = sentence.split() word_lengths =  for word in words: if word != "the": word_lengths.append(len(word))
Using a list comprehension, we could simplify this process to this notation:
sentence = "the quick brown fox jumps over the lazy dog" words = sentence.split() word_lengths = [len(word) for word in words if word != "the"]
Using a list comprehension, create a new list called "newlist" out of the list "numbers", which contains only the positive numbers from the list, as integers.