def add_list_data(data)
      raise symbol.to_s if data.nil?
      self.exchange_rate = data['price_usd'].to_f
      self.perchant_change_week = data['percent_change_7d'].to_f
      self.perchant_change_day = data['percent_change_24h'].to_f
    end
def add_list_data(data)
      raise symbol.to_s if data.nil?
      self.exchange_rate = data['price_usd'].to_f
      self.perchant_change_week = data['percent_change_7d'].to_f
      self.perchant_change_day = data['percent_change_24h'].to_f
    end
Builds a UserPair given the related CMC data