Array flatten

function array_flatten ( $a )
	{ //flattens multi-dim arrays (distroys keys)
		$ab = array ();
		if ( ! is_array ( $a ) ) {
			return $ab;
		}
		
		foreach ( $a as $value )
		{
			if ( is_array ( $value ) ) {
				$ab = array_merge ( $ab, array_flatten ( $value ) );
			}
			else {
				array_push ( $ab, $value );
			}
		}
		return $ab;
	}