human
I wrote the below code

    importer = get_importer(path_item)
    if (importer is None):
        return None
    loader = importer.find_module(packageName)
    if (loader is None):
        return None
    module = sys.modules.get(packageName)
    if (module is None):
        module = sys.modules[packageName] = types.ModuleType(packageName)
        module.__path__ = []
        _set_parent_ns(packageName)
    elif (not hasattr(module, '__path__')):
        raise TypeError('Not    a    package:', packageName)
    handler = _find_adapter(_namespace_handlers, importer)
    subpath = handler(importer, path_item, packageName, module)
    if (subpath is not None):
        path = module.__path__
        path.append(subpath)
        loader.load_module(packageName)
        sys_path = [((p and _normalize_cached(p)) or p) for p in sys.path]
        def sort_key(p):
            parts = p.split(os.sep)
            parts = parts[:(- (packageName.count('.') + 1))]
            return sys_path.index(_normalize_cached(os.sep.join(parts)))
        path.sort(key=sort_key)
        module.__path__[:] = [_normalize_cached(p) for p in path]
    return subpath

What's a good function header?
assistant
#Here's a good function header.

def _handle_ns(packageName, path_item):