code: function () {
                  if (this.min == 0 && this.max == 1)
                      return this.firstChild.toString() + "?";
                  if (this.min == 0 && this.max == Infinity)
                      return this.firstChild.toString() + "*";
                  if (this.min == 1 && this.max == Infinity)
                      return this.firstChild.toString() + "+";
                  return this.firstChild.toString() + "{" + this.min + "," + this.max + "}";
              }
docs: Used for creating a human readable definition of the grammar.