Method appendleft

DSA/deque.py:36–41

(self, x)

        self.tail %= self.length

    def appendleft(self, x):
        if self.is_full():
            self.__extend()
        self.buf[(self.head - 1) % self.length] = x
        self.head -= 1
        self.head %= self.length

    def pop(self):
        if self.is_empty():