labelme file structure: for each JSON file, should I have a folder with the same name inside the directory?

[HydrogenEwan]

Hi I'd like to thank for your great work first!

And I wonder in the following code, where I have marked in the comment MARK1 and MARK2

def _train_test_split(self, folders, json_names, val_size):
        if len(folders) > 0 and 'train' in folders and 'val' in folders:
            train_folder = os.path.join(self._json_dir, 'train/')
            train_json_names = [train_sample_name + '.json' \
                                for train_sample_name in os.listdir(train_folder) \
                                if os.path.isdir(os.path.join(train_folder, train_sample_name))] # MARK1
            
            val_folder = os.path.join(self._json_dir, 'val/')
            val_json_names = [val_sample_name + '.json' \
                              for val_sample_name in os.listdir(val_folder) \
                              if os.path.isdir(os.path.join(val_folder, val_sample_name))] # MARK2
            
            return train_json_names, val_json_names
        
        train_idxs, val_idxs = train_test_split(range(len(json_names)), 
                                                test_size=val_size)
        train_json_names = [json_names[train_idx] for train_idx in train_idxs]
        val_json_names = [json_names[val_idx] for val_idx in val_idxs]
        
        return train_json_names, val_json_names

I think MARK1 and MARK2 are asking each JSON file to have a folder with the same name under that folder. I wonder if this is correct and the purpose of doing so.

Thanks!