public static function SendContentType( string $mimetype = 'text/html', string $charset = 'utf-8' )
   {

      if ( empty( $charset ) )
      {
         \header( 'Content-Type: ' . $mimetype );
      }
      else
      {
         \header( 'Content-Type: ' . $mimetype . '; charset=' . $charset );
      }

   }