Before we begin our exercise, we should go over the Python
for loop one more time. For now, we are only going to go over the
for loop in terms of how it relates to lists and dictionaries. We'll explain more cool
for loop uses in later courses.
for loops allow us to iterate through all of the elements in a list from the left-most (or zeroth element) to the right-most element. A sample loop would be structured as follows:
a = ["List of some sort”] for x in a: # Do something for every x
This loop will run all of the code in the indented block under the
for x in a: statement. The item in the list that is currently being evaluated will be
x. So running the following:
for item in [1, 3, 21]: print item
would print 1, then 3, and then 21. The variable between
in can be set to any variable name (currently
item), but you should be careful to avoid using the word “list” as a variable, since that's a reserved word (that is, it means something special) in the Python language.