parseXRDS (OpenID::Yadis)

    # File lib/openid/yadis/xrds.rb, line 90
        def Yadis::parseXRDS(text)
          if text.nil?
            raise XRDSError.new("Not an XRDS document.")
          end

          begin
            d = REXML::Document.new(text)
          rescue RuntimeError => why
            raise XRDSError.new("Not an XRDS document. Failed to parse XML.")
          end

          if is_xrds?(d)
            return d
          else
            raise XRDSError.new("Not an XRDS document.")
          end
        end