function _existRem( &$array, $expkey, $expval=FALSE, $hitval=null ) {
    if( !is_array( $array ) || ( 0 == count( $array )))
      return null;
    if( !isset( $array[$expkey] ))
      return null;
    if( !$expval )
      return $hitval;
    if( $expval != $array[$expkey] )
      return null;
    unset( $array[$expkey] );
    return $hitval;
  }