code: function(value, name) {
  
  		var result = false,
  			index = this._data_values.indexOf(value);
  
  		if (index == -1) {
  			this.push(value, name);
  			result = true;
  		}
  
  		return result;
  
  	}
docs: If value does not exist - push it into collection
  @param {*} value New value
  @param {string} [name] New name
  @returns {boolean} <kw>true</kw>, if value did not exist and was included