def exchange(original, target, amount)
      negative = (@numeric < 0)

      rate = call_xavier_api(original, target)
     #
      # Get the result and round it to 2 decimals
      result = sprintf("%.2f", amount * rate).to_f

      return -(result) if negative
      result
    end
def exchange(original, target, amount)
      negative = (@numeric < 0)

      rate = call_xavier_api(original, target)
     #
      # Get the result and round it to 2 decimals
      result = sprintf("%.2f", amount * rate).to_f

      return -(result) if negative
      result
    end
Main method (called by _to) which calls Xavier API
 and returns a nice result.