docs: function (store, type, fixtureRecord) {
      var fixture, fixturesArray;
      if (fixtureRecord.id) {
        fixture = this.fixtureForId(store, type, fixtureRecord.id);
        if (fixture) {
          fixturesArray = this.fixturesForType(store, type);
          fixturesArray.splice(fixturesArray.indexOf(fixtureRecord), 1);
        }
      }
      else {
        throw new Error('Deleting a fixture requires an ID.');
      }
      return null;
    }