flatten an multidimensional array and combine keys with separator

gistfile1.php

<?php

$flatten = function( $array , $keySeparator = '.' ) use ( & $flatten )
{
	if( is_array( $array ) ) {
		foreach( $array as $name => $value ) {
			$f = $flatten( $value , $keySeparator );
			if( is_array( $f ) ) {
				foreach( $f as $key => $val ) {
					$array[ $name . $keySeparator . $key ] = $val;
				}
				unset( $array[ $name ] );
			}
		}
	}
	return $array;
};

public static function array_flatten( $array , $keySeparator = '__' )
    {
        if( is_array( $array ) ) {
            foreach( $array as $name => $value ) {
                $f = self::array_flatten( $value , $keySeparator );
                if( is_array( $f ) ) {
                    foreach( $f as $key => $val ) {
                        $array[ $name . $keySeparator . $key ] = $val;
                    }
                    unset( $array[ $name ] );
                }
            }
        }
        return $array;
    }