sub wrap {
  my ($old_body, $environment) = @_;


  my $new_body = <<'__WRAP__';

    #---PRE_BODY
    my $foo++;      # new var

    #<OLD_BODY>#

    #--- POST_BODY
    print $foo;

__WRAP__

  $new_body =~ s/#<OLD_BODY>#/$old_body/g;


  my $code = eval_closure(
      source      => "sub { $new_body }",
      environment => $environment,
  );

}