mixin.php

<?php
/**
 * @mixin \Illuminate\Support\Collection
 * 
 * @psalm-suppress UndefinedMethod
 * @psalm-suppress UndefinedThisPropertyFetch
 * @psalm-suppress UndefinedThisPropertyAssignment
 */
class CollectionMixin
{
    public function fill()
    {
        return function ($value) {
            /** @var \Illuminate\Support\Collection $this */
            return $this->map(fn () => $value);
        };
    }
}