code: function(model, options) {
              model = this._prepareModel(model, options);
              this.add(model, options);
              return model;
          }
docs: Add a model at the end of the collection.
  
  @method push
  @param {Model} model model or data to add
  @param {object} [options] options for adding
  @return {Model} Return the new added model