What does calling a function means in Python

Question

What is the significance of calling a function? In python what does it mean?

Answer 1

Calling a function means that you are making a reference to the function which is written somewhere else. For example:

#!/usr/env python
import os
def foo():
    return "hey let's understand calling a function"
print os.getlogin()
print foo()

This is how you call a function.