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sub dostuff {
  my %arg = @_;
...
}

dostuff( foo => 'FOO', bar => 1 );

sub_with_callbacks (
  red    => sub { my %arg = @_; .. $arg{foo} .. },
...
  blue   => sub { my %arg = @_; .. $arg{foo} .. },
  yellow => sub { my %arg = @_; .. $arg{foo} .. }
);

sub_with_callbacks (
  red    => sub { .. $_{foo} .. },
...
  blue   => sub { .. $_{foo} .. },
  yellow => sub { .. $_{foo} .. }
);