code: function removeElements(collection, newCollection, index) {
          if (index === void 0) { index = 'id'; }
          var oldLength = collection.length;
          _.remove(collection, function (item) { return !_.some(newCollection, function (c) { return c[index] === item[index]; }); });
          return collection.length !== oldLength;
      }
docs: Removes elements in the target array based on the new collection, returns true if
  any changes were made