A main function

• main
• def

You could write your code in the main body of your Python file, but using functions and passing arguments to it will make your code easier to maintain and understand. Therefore I recommend that you always write every script with a function called "main".

• Function definition starts with the def keyword, followed by the name of the new function ("main" in this case), followed by the list of parameters in parentheses (nothing in this case).
• The content or body of the function is then indented to the right.
• The function definition ends when the indentation stops.

If you execute this file you might be surprised that nothing happens. This is so because we only defined the function, we never used it. We'll do that next.

def main():
    print("Hello")
    print("World")

This won't run as the main function is declared, but it is never called (invoked).