Guess strategy type to use for file by extension.

    Args:
        file_name_or_ext: Either a file name with an extension or just
            an extension

    Returns:
        Strategy: Type corresponding to extension or None if there's no
            corresponding strategy type

def guess_strategy_type(file_name_or_ext):
    """Guess strategy type to use for file by extension.

    Args:
        file_name_or_ext: Either a file name with an extension or just
            an extension

    Returns:
        Strategy: Type corresponding to extension or None if there's no
            corresponding strategy type

    """
    if '.' not in file_name_or_ext:
        ext = file_name_or_ext
    else:
        name, ext = os.path.splitext(file_name_or_ext)
    ext = ext.lstrip('.')
    file_type_map = get_file_type_map()
    return file_type_map.get(ext, None)