TRY ADDING BRACES TO f IN ORDER TO SHOW THAT f IS THE NAME OF A
FUNCTION; EVEN THOUGH THE BRACES ARE NOT PART OF THE FUNCTION'S NAME

def print_doof():
    print('doof')

f() = print_doof


def mach_n(f,n):
    if n <= 0:
        return
    f()
    mach_n(f,n-1)
    

mach_n(f,6)

RUN MODULE

MESSAGE: SYNTAX ERROR. CAN'T ASSIGN f() = print_doof
TO FUNCTION CALL