code: function ( obj, arg ) {
  		if ( !array.contains( obj, arg ) ) {
  			obj.push( arg );
  		}
  
  		return obj;
  	}
docs: Adds 'arg' to 'obj' if it is not found
  
  @method add
  @param  {Array} obj Array to receive 'arg'
  @param  {Mixed} arg Argument to set in 'obj'
  @return {Array}     Array that was queried