%hash = (
  HELP => sub { ... },
  '?' => $_{HELP},
  QUIT => sub { ... },
  EXIT => $_{QUIT},
  LEAVE => $_{QUIT},
);

##</code><code>##

%hash = (
  HELP => sub { ... },
  QUIT => sub { ... },
);
$hash{'?'} = $hash{HELP};
$hash{EXIT} = $hash{LEAVE} = $hash{QUIT};