getOrPut() can be used to fetch an item if it already exists, or insert it and fetch it if it doesn't. This can be really useful when building up a Collection with data from multiple sources and don't want duplicate items in our data.

get-or-put-collection.php

// ❌
if (! $collection->has($key)) {
    $collection->put($key, $this->builtItem($data));
}
 
return $collection->get($key);

// ✔️
return $collection->getOrPut($key, fn () => $this->buildItem($data));