A resource repository is similar to a filesystem. It stores {@link PuliResource}
objects, each of which has a path in the repository:
php
$resource = $repo->get('/css/style.css');
Resources may have child resources. These can be accessed with
{@link listChildren()}:
php
$resource = $repo->get('/css');
foreach ($resource->listChildren() as $name => $resource) {
...
}