public static function FromFormat( string $format, $time, \DateTimeZone $timezone = null ) : DateTime
   {
      if ( $timezone !== null )
      {
         $dt = parent::createFromFormat( $format, $time, $timezone );
      }
      else
      {
         $dt = parent::createFromFormat( $format, $time );
      }

      if ( $dt instanceof \DateTime )
      {
         return static::FromDateTime( $dt );
      }

      throw new ArgumentError(
         'format',
         $format,
         'Date',
         \join( \PHP_EOL, parent::getLastErrors() )
      );

   }