Hashes are great for storing named data, but if you want more than one entry
for a name, you have to use a list of pairs. Even then, this is really boring
to write:
$values = [
foo => undef,
bar => undef,
baz => undef,
xyz => { ... },
];
With Data::OptList, you can do this instead:
$values = Data::OptList::mkopt([
qw(foo bar baz),
xyz => { ... },
]);
This works by assuming that any defined scalar is a name and any reference
following a name is its value.
