code: function(instances, grouped) {
      instances.forEach(function(instance) {
        var pk = instance.getAttribute(this.primaryKeyAttr);
        var results = grouped[pk] || [];
        this.associateFetchedObjects(instance, results);
      }, this);
    }
docs: Override of {@link BaseRelation#associatePrefetchResults}.
  
  Mixins can override {@link HasMany#associatePrefetchResults} to change the
  way pre-fetch association is performed. This is the default
  implementation.
  
  @method
  @protected
  @see {@link BaseRelation#associatePrefetchResults}