code: function wrapGetterFn(_ref) {
          var _ref2 = slicedToArray(_ref, 2),
              key = _ref2[0],
              originalFn = _ref2[1];
  
          var newFn = function newFn() {
              var innerFn = originalFn.apply(this, arguments);
  
              if (typeof innerFn !== 'function') {
                  /* istanbul ignore next */
                  throw 'The getter ' + key + ' does not return a function. Try using the \'mapGetter\' helper instead';
              }
  
              return innerFn(this.id);
          };
  
          return [key, newFn];
      }
docs: Create a wrapper function which invokes the original function passing in `this.id`