function address 3

def a(x, y):
    print("I am from function a")
    return x(y)
def b(z):
    z()
    def c():       #register the address of function c with the content below. Function c is not run until function c is called outside on line 9.
        print("I am from function c")
    print("I am from function b")
    return c #return must be placed at the end of the function
def d():
    print("I am from function d")
a(b,d)()