':param tick: The tick with the price to be relative to
:type tick: Tick
:return: The relative price
:rtype: Price'

def relative_tick_price(self, tick):

    assert isinstance(tick, Tick), type(tick)
    if tick.is_ask():
        return self.ask_relative_price(tick.price)
    else:
        return self.bid_relative_price(tick.price)
