foreach my $key ( @keys ) {

    if ( ! defined ( $self->{'output'}->{$key}->{'fh'} )
         && $self->{'output'}->{$key}->{'type'} ne 'named_pipe' ) {
      croak "undefined fh for key $key\n";
    }

    given ( $self->{'output'}->{$key}->{'type'} ) {

      when ('named_pipe') {
        open my $handle, '>', $self->{'output'}->{$key}->{'name'}
          or croak "open failed: $!";
        
        print $handle $input;
        close $handle or croak "close failed: $!";
      }

    }

  }