code: function (args) {
        args = args || [];
        var str = args[0];
  
        if (str) {
          str = str.toUpperCase();
          if (instance.formulas[str]) {
            return ((typeof instance.formulas[str] === 'function') ? instance.formulas[str].apply(this, args) : instance.formulas[str]);
          }
        }
  
        throw Error('NAME');
      }
docs: get variable from formula
  @param {Array} args
  @returns {*}