should function be defined before it is used in python?

Question

should the functions be defined before it is used? but why the following code works:

def main():
    dog()

def dog():
    print("This is a dog.")

if __name__ == '__main__':
    main()

I mean the dog() is defined after it is called, how this works?

Answer 1

Actually it's not (defined after it's called). This script will do the following:

• create function and assign it to "main"
• create function and assign it to "dog"
• call "main"

At that point dog is already known in global scope and main can call it.