lib/datatrans/xml/transaction.rb
def method_missing(method, *args, &block)
      if response.respond_to? method.to_sym
        response.send(method)
      elsif request.respond_to? method.to_sym
        request.send(method)
      else
        super
      end
    end
def method_missing(method, *args, &block)
      if response.respond_to? method.to_sym
        response.send(method)
      elsif request.respond_to? method.to_sym
        request.send(method)
      else
        super
      end
    end
TODO: purchase, credit methods