def fun1(x,y):
    x = 30
    y = 40
    z = fun2(x)
    w = fun3(fun4(z),y)
    print("fun1, x,y,z,w:",x,y,z,w)
    return x + y

def fun2(y):
    print("fun2, y:",y)
    return y + 1

def fun4(x):
    print("fun4, x:",x)
    return x - 1

def fun3(z,y):
    print("fun3, z,y:",z,y)
    for i in range(3):
        print("fun3, i:",i)
    return z

def main():
    x = 1
    y = 2
    z = fun1(x,y)
    print("main, x,y,z:",x,y,z)

main()