code: function operator(value) {
      var raw = this.unwrapRaw(value);
      if (raw) {
        return raw;
      }
      if (operators[(value || '').toLowerCase()] !== true) {
        throw new TypeError('The operator "' + value + '" is not permitted');
      }
      return value;
    }
docs: The operator method takes a value and returns something or other.