docs: function recurse( out, arr, depth ) {
  	var len = arr.length,
  		val,
  		i;
  
  	for ( i = 0; i < len; i++ ) {
  		val = arr[ i ];
  		if ( depth && isArray( val ) ) {
  			recurse( out, val, depth-1 );
  		} else {
  			out.push( val );
  		}
  	}
  	return out;
  }