code: function concat( arr ) {
  	var i;
  	for ( i = 1; i < arr.length; i++ ) {
  		arr[ 0 ] = arr[ 0 ].concat( arr[ i ] );
  	}
  	return arr[ 0 ];
  }
docs: FUNCTION: concat( arr )
  Concatenates an array of arrays.
  
  @param {Array[]} arr - array of arrays
  @returns {Array} concatenated array