# File lib/qbxml/response.rb, line 18
    def <<(qbxml_response)
      if qbxml_response.is_a?(Qbxml::Response)
        set << qbxml_response
      elsif qbxml_response.respond_to?(:each)
        qbxml_response.each do |response|
          self << response
        end
      else
        raise ArgumentError, "Cannot add object of type #{qbxml_response.class.name} to a Qbxml::ResponseSet"
      end
    end