Detectando Tokens

def recebe_seq(vetor):
    aux = []
    tokens = {']': '[', '}': '{', ')': '('}
    for i in vetor:
        if i in tokens.values():
            aux.append(i)
        else:
            if len(aux) == 0 or tokens[i] != aux[-1]:
                return False
            aux = aux[:-1]
    return len(aux) == 0