code: function(){
        var base = Utils.unwrapValue(this, 'baseUrl') || (this.collection && Utils.unwrapValue(this.collection, 'url'));
        if(typeof base === undefined) throw "Missing baseUrl or collection.url properties";
        if(this.isNew()) return base;
        return base + (base[base.length-1] === '/' ? '' : '/') + this.id();
      }
docs: Returns the model url using model's baseUrl or collection's url properties. If they're both undefined, throw an error If model.id() is set add model.id() to the url