public function setCharset( string $charset = 'UTF8' ) : MySQL
   {

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

      $this->_attributes[ 'charset' ] = $charset;

      return $this;

   }