The foo() function returns an arrayref, each element of which
represents a bar that I have visited.  Each bar is a hashref with
the following keys:

=head2 name, address, phone

The bar's name, address and phone number

=head2 good_beer

An optional key, which if present will be a hashref of beers,
whose keys are the beers' names and the values are the breweries
that make them.

=head2 cute_staff

An optional key, which if present will be an arrayref (one element
per cute staff member) of hashrefs, with keys 'name', 'sex',
'preferred_sex' and 'phone'.

...

For example:

    [
        {
            name    => 'The Traditional Pub,
            address => '13 Wharf St, Workingclasstown',
            phone   => '01234 567890',
            good_beer => {
                'Tanglefoot'   => 'Badger',
                'Paradise Ale' => 'Theakstons',
                'Special'      => 'Youngs'
            },
            cute_staff => [ # array in case there's two with the
                {           # same name
                    name => 'Jill',
                    sex  => 'F',
                    preferred_sex => 'M',
                    phone => '01234567899'
                } ...
            ]
        },
        ...
    ]