Метод 1: вложенные функции

def outer_function():
    def inner_function():
        print("This is the inner function.")
    print("This is the outer function.")
    inner_function()
outer_function()

Выход:

This is the outer function.
This is the inner function.

Метод 2. Возврат функции

def outer_function():
    def inner_function():
        print("This is the inner function.")
    print("This is the outer function.")
    return inner_function
func = outer_function()
func()

Выход:

This is the outer function.
This is the inner function.

Метод 3: функция как аргумент

def outer_function(inner_function):
    print("This is the outer function.")
    inner_function()
def inner_function():
    print("This is the inner function.")
outer_function(inner_function)

Выход:

This is the outer function.
This is the inner function.