def METHOD_NAME(names: Any) -> Dict[str, str]:
    if names is None:
        return {}
    if not isinstance(names, dict):
        raise UsageError("Expected key-value list for names in country_settings.py")
    flat = {}
    for prefix, remain in names.items():
        if isinstance(remain, str):
            flat[prefix] = remain
        elif not isinstance(remain, dict):
            raise UsageError("Entries in names must be key-value lists.")
        else:
            for suffix, name in remain.items():
                if suffix == 'default':
                    flat[prefix] = name
                else:
                    flat[f'{prefix}:{suffix}'] = name
    return flat