<?php     public static function becauseTheFilesystemWasNotValid($filesystem): UnableToMountFilesystem
    {
        $received = is_object($filesystem) ? get_class($filesystem) : gettype($filesystem);
        return new UnableToMountFilesystem(
            'Unable to mount filesystem, filesystem was invalid. Instance of ' . FilesystemOperator::class . ' expected, received: ' . $received