def build_xml( result )
      xml = ::Builder::XmlMarkup.new
    
      xml.ProcessResponse do 
        xml.PxPayUserId ::Pxpay::Base.pxpay_user_id
        xml.PxPayKey ::Pxpay::Base.pxpay_key
        xml.Response result
      end
    end
def build_xml( result )
      xml = ::Builder::XmlMarkup.new
    
      xml.ProcessResponse do 
        xml.PxPayUserId ::Pxpay::Base.pxpay_user_id
        xml.PxPayKey ::Pxpay::Base.pxpay_key
        xml.Response result
      end
    end
Internal method to build the xml to send to Payment Express