':type tick: TickEntry'

def append_tick(self, tick):

    assert isinstance(tick, TickEntry), type(tick)
    assert (tick.quantity.wallet_id == self._quantity_wallet_id)
    if (self._length == 0):
        tick.prev_tick = None
        tick.next_tick = None
        self._head_tick = tick
        self._tail_tick = tick
    else:
        tick.prev_tick = self._tail_tick
        tick.next_tick = None
        self._tail_tick.next_tick = tick
        self._tail_tick = tick
    self._length += 1
    self._depth += tick.quantity
