#wrapper
def push_(pila,elemento):
    pila.append(elemento)

def pop_(pila):
    return pila.pop()

def main():
    stack = ["a","b","c","d"]
    push_(stack,"z")
    print(stack)
    x = pop_(stack)
    print(x)
    print(stack)

if __name__ == "__main__":
    main()