code: function(obj) {
          if (obj !== null) {
              if (this.qs === null) {
                  this.qs = '';
              }
  
              if (this.qs.length > 0) {
                  this.qs = this.qs + "&" + URI.toQS(obj);
              } else {
                  this.qs = URI.toQS(obj);
              }
          }
      }
docs: Append the given parameters to a query string of the URI.
  @param  {Object} obj a dictionary of parameters to be appended to
  the URL query string
  @method appendQS