assets/js/vendor/backbone-relational.js
function( model ) {
			var reverseRelations = [];
			// Iterate over 'model', 'this.related.models' (if this.related is a Backbone.Collection), or wrap 'this.related' in an array.
			var models = !_.isUndefined( model ) ? [ model ] : this.related && ( this.related.models || [ this.related ] );
			_.each( models || [], function( related ) {
				_.each( related.getRelations() || [], function( relation ) {
						if ( this._isReverseRelation( relation ) ) {
							reverseRelations.push( relation );
						}
					}, this );
			}, this );

			return reverseRelations;
		}
function( model ) {
			var reverseRelations = [];
			// Iterate over 'model', 'this.related.models' (if this.related is a Backbone.Collection), or wrap 'this.related' in an array.
			var models = !_.isUndefined( model ) ? [ model ] : this.related && ( this.related.models || [ this.related ] );
			_.each( models || [], function( related ) {
				_.each( related.getRelations() || [], function( relation ) {
						if ( this._isReverseRelation( relation ) ) {
							reverseRelations.push( relation );
						}
					}, this );
			}, this );

			return reverseRelations;
		}
Get the reverse relations (pointing back to 'this.key' on 'this.instance') for the currently related model(s).
@param {Backbone.RelationalModel} [model] Get the reverse relations for a specific model.
If not specified, 'this.related' is used.
@return {Backbone.Relation[]}