function(data, track) {
		if (track !== false) data = $track(data, track);
		this.data = data;
		this._dep.changed();
		return this;
	}
function(data, track) {
		if (track !== false) data = $track(data, track);
		this.data = data;
		this._dep.changed();
		return this;
	}
function ( data , track ) { if ( track !== false ) data = $track ( data , track ) ; this . data = data ; this . _dep . changed ( ) ; return this ; }
sets the data on the model
sets the data on the model