def parse_cooler_uri(s):
    """
    Parse a Cooler URI string

    e.g. /path/to/mycoolers.cool::/path/to/cooler

    """
    parts = s.split("::")
    if len(parts) == 1:
        file_path, group_path = parts[0], "/"
    elif len(parts) == 2:
        file_path, group_path = parts
        if not group_path.startswith("/"):
            group_path = "/" + group_path
    else:
        raise ValueError("Invalid Cooler URI string")
    return file_path, group_path