code: function () {
              var x3 = this.dpop();
              var x2 = this.dpop();
              var x1 = this.dpop();
              this.dpush(x2);
              this.dpush(x3);
              this.dpush(x1);
          }
docs: rot ( x1 x2 x3 -- x2 x3 x1 )