sub XML_elem {
  my $tag = shift;
  my @results; # return value

  my $attribs = shift @_ if( ref( $_[0] ) eq 'HASH' );

  push @results, "<${tag}" . stringify_attribs( $attribs ) . ">";

  if( @_ == 0 ) { # handle an empty element
    $results[0] =~ s|>$| />|;
    return @results;
  }

  foreach my $arg ( @_ ) {
    if( ref( $arg ) eq 'CODE' ) {
      push @results, map{ "  $_" } $arg->(); # <--- ???
    } else {
      push @results, '  ' . escape_ents( $arg )
    }
  }

  push @results, "<\\${tag}>";
  return @results;
}