Implement a ring buffer

class RingBuffer:
    def __init__(self, capacity):
        self.size = capacity
        self.capacity = 0
        self.Buffer = [None] * capacity
        self.Head = 0
        self.Tail = 0

    def full(self):
        return self.size == self.capacity

    def empty(self):
        return self.capacity == 0

    def add(self, obj):
        self.Buffer[self.Tail] = obj
        self.Tail = (self.Tail   1) % self.size
        Self.capacity  = 1

    def pop(self):
        self.Head = (self.Head   1) % self.size
        Self.capacity -= 1
        return self.Buffer[self.Head - 1]