collections deque没有属性'appendLeft'

Question

我正在尝试使用收藏库中的双端队列，但出现错误：

'collections.deque'对象没有属性'appendLeft'。

我不太确定这里发生了什么...我正在导入库并按照文档使用。我必须错过一些确实很明显的东西，但不能动弹。

import unittest
import collections

class animal_shelter():
    def __init__(self):
        self.cats = collections.deque()
        self.dogs = collections.deque()

    def enqueue(self, animal):
        if animal.type == 'dog':
            self.dogs.appendLeft(animal)
        elif animal.type == 'cat':
            self.cats.appendLeft(animal)

    def dequeue_cat(self):
        if len(self.cats) > 0:
            return self.cats.pop().name
        else:
            return None

    def dequeue_dog(self):
        if len(self.dogs) > 0:
            return self.dogs.pop().name
        else:
            return None

    def is_empty(self):
        return len(self.dogs) == 0 and len(self.cats) == 0

    def dequeue_any(self):
        if self.is_empty():
            return None
        if len(self.dogs) >= len(self.cats):
            return self.dogs.pop().name
        else:
            return self.cats.pop().name

class Test(unittest.TestCase):
    def test_simple(self):
        shelter = animal_shelter()

        shelter.enqueue(Animal('dog', 'rex'))
        shelter.enqueue(Animal('dog', 'max'))
        shelter.enqueue(Animal('cat', 'felix'))

        self.assertEqual(shelter.dequeue_any(), 'rex')
        self.assertEqual(shelter.dequeue_cat(), 'felix')
        self.assertEqual(shelter.dequeue_cat(), None)
        self.assertEqual(shelter.dequeue_dog(), 'max')
        self.assertEqual(shelter.dequeue_any(), None)

class Animal():
    def __init__(self, type, name):
        self.type = type
        self.name = name

if __name__ == "__main__":
    unittest.main()

Traceback (most recent call last):
  File "animal_shelter.py", line 42, in test_simple
    shelter.enqueue(Animal('dog', 'rex'))
  File "animal_shelter.py", line 11, in enqueue
    self.dogs.appendLeft(animal)
AttributeError: 'collections.deque' object has no attribute 'appendLeft