public function setUnixSocket( ?string $socket ) : MySQL
   {

      if ( ! $this->_supportedAttributes->get( 'unix_socket' )->validateValue( $socket ) )
      {
         throw new ArgumentException( 'socket', $socket, 'Invalid unix socket!' );
      }

      $this->_attributes[ 'unix_socket' ] = $socket;

      return $this;

   }