def exists_lazy(path, data_type='data'):
    """
    Check if we've already made a lazy version of this file for the `data_type` field.
    """
    if not os.path.exists(get_lazy_path(path)):
        return False
    contents = os.listdir(get_lazy_path(path))
    if data_type not in contents:
        return False
    if data_type + '.len.pkl' not in contents:
        return False
    return True

    Check if we've already made a lazy version of this file for the `data_type` field.
    
megatron_lm/megatron/deprecated_data_utils/lazy_loader.py