if ($SIG{__WARN__}) {
      my $previous = $SIG{__WARN__};
      my $caught = 0;
      $SIG{__WARN__} = sub {
          return if $caught;
          $caught = 1;
          # do my stuff
          my $ret = $previous->();
          $caught = 0;
          return $ret;
      };
    }
    else