Understanding Python 3 lists printing None value for each element

Question

As a very noob with in Python I'm printing all elements of a list in version 3, and after a comprehensive research I couldn't find an explanation for this kind of behavior.

However, I know every function must return some value and when it's not defined the function returns "Null" (or "None" in Python). But why in this case, after printing all elements correctly it prints "None" for each element in another list?

>>> a_list = [1,2]
>>> a_list
[1, 2]
>>> [print(f) for f in a_list]
1
2
[None, None]

Answer 1

None is the return value of the print function.

Don't use [print(f) for f in a_list] when you mean for f in a_list: print(f).