whole_func_string: function() {
      const ch = this._input[this.offset - 1];
      const fn = this.tokenTerminals[ch];
      if (fn) {
        return fn.apply(this, []);
      } else {
        return this.yytext;
      }
    }
func_code_string: function() {
      const ch = this._input[this.offset - 1];
      const fn = this.tokenTerminals[ch];
      if (fn) {
        return fn.apply(this, []);
      } else {
        return this.yytext;
      }
    }
func_documentation_string: reads a custom token