How to use the watchgod.watcher.DefaultDirWatcher function in watchgod

deleted = self.files.keys() - new_files.keys()
        if deleted:
            changes |= {(Change.deleted, entry) for entry in deleted}

        self.files = new_files
        return changes


class DefaultDirWatcher(AllWatcher):
    ignored_dirs = {'.git', '__pycache__', 'site-packages', '.idea', 'node_modules'}

    def should_watch_dir(self, entry):
        return entry.name not in self.ignored_dirs


class DefaultWatcher(DefaultDirWatcher):
    ignored_file_regexes = r'\.py[cod]$', r'\.___jb_...___$', r'\.sw.$', '~$'

    def __init__(self, root_path):
        self._ignored_file_regexes = tuple(re.compile(r) for r in self.ignored_file_regexes)
        super().__init__(root_path)

    def should_watch_file(self, entry):
        return not any(r.search(entry.name) for r in self._ignored_file_regexes)


class PythonWatcher(DefaultDirWatcher):
    def should_watch_file(self, entry):
        return entry.name.endswith(('.py', '.pyx', '.pyd'))


class RegExpWatcher(AllWatcher):

def should_watch_dir(self, entry):
        return entry.name not in self.ignored_dirs


class DefaultWatcher(DefaultDirWatcher):
    ignored_file_regexes = r'\.py[cod]$', r'\.___jb_...___$', r'\.sw.$', '~$'

    def __init__(self, root_path):
        self._ignored_file_regexes = tuple(re.compile(r) for r in self.ignored_file_regexes)
        super().__init__(root_path)

    def should_watch_file(self, entry):
        return not any(r.search(entry.name) for r in self._ignored_file_regexes)


class PythonWatcher(DefaultDirWatcher):
    def should_watch_file(self, entry):
        return entry.name.endswith(('.py', '.pyx', '.pyd'))


class RegExpWatcher(AllWatcher):
    def __init__(self, root_path, re_files=None, re_dirs=None):
        self.re_files = re.compile(re_files) if re_files is not None else re_files
        self.re_dirs = re.compile(re_dirs) if re_dirs is not None else re_dirs
        super().__init__(root_path)

    def should_watch_file(self, entry):
        return self.re_files.match(entry.path)

    def should_watch_dir(self, entry):
        return self.re_dirs.match(entry.path)