def removeTail(self):
    if (self.size() == 0):
        return None
    else:
        value = deepcopy(self.data[(- 1)])
        del self.data[(- 1)]
        return value
def removeTail(self):
    if (self.size() == 0):
        return None
    else:
        value = deepcopy(self.data[(- 1)])
        del self.data[(- 1)]
        return value