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sub body {
  my ($tab,$code,$opt) = @_;
...
  &$code;
  line($tab,"</$tag>");
}

body( sub {
  header( sub {
...
    ... some footer code for the body ...
  });
});

sub body {
  my ($tab,$opt) = @_;
...
  footer($tab + 1, @{$opt->{footer}}) if $opt->{footter};
  line($tab,"</$tag>");
}

body(
  header => sub {
...
    );
  },
);