code: function _create(c, i) {
          var o = {};
              o.id = Y.Lang.isNumber(i) ? i : _id();
              c = c || {};
  
          if (!c.use && !c.upload) {
              o.c = _xhr();
          }
          else if (c.use) {
              if (c.use === 'native') {
                  if (w.XDomainRequest) {
                      o.c = new XDomainRequest();
                      o.t = c.use;
                  }
                  else {
                      o.c = _xhr();
                  }
              }
              else {
                  o.c = Y.io._transport[c.use];
                  o.t = c.use;
              }
          }
          else {
              o.c = {};
          }
  
          return o;
      }
docs: @description Method that creates a unique transaction object for each
  request.
  
  @method _create
  @private
  @static
  @param {number} c - configuration object subset to determine if
  the transaction is an XDR or file upload,
  requiring an alternate transport.
  @param {number} i - transaction id
  @return object