code: def price_ticks_away(price, n_ticks):
      
      price_index = PRICES.index(as_dec(price))
      return float(PRICES[price_index + n_ticks])
docs: Returns an exact, valid Betfair price that is n_ticks "ticks" away from
      the given price. n_ticks may positive, negative or zero (in which case the
      same price is returned) but if there is no price n_ticks away from the
      given price then an exception will be thrown.
  
      :param float price: An exact, valid Betfair price
      :param float n_ticks: The number of ticks away from price the new price is
      :returns: An exact, valid Betfair price
      :rtype: float