src/model.js
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