How to use the gtts.lang.tts_langs function in gTTS

def print_languages(ctx, param, value):
    """Callback for  flag.
    Prints formatted sorted list of supported languages and exits
    """
    if not value or ctx.resilient_parsing:
        return
    try:
        langs = tts_langs()
        langs_str_list = sorted("{}: {}".format(k, langs[k]) for k in langs)
        click.echo('  ' + '\n  '.join(langs_str_list))
    except RuntimeError as e:  # pragma: no cover
        log.debug(str(e), exc_info=True)
        raise click.ClickException("Couldn't fetch language list.")
    ctx.exit()

):

        # Debug
        for k, v in locals().items():
            if k == 'self':
                continue
            log.debug("%s: %s", k, v)

        # Text
        assert text, 'No text to speak'
        self.text = text

        # Language
        if lang_check:
            try:
                langs = tts_langs()
                if lang.lower() not in langs:
                    raise ValueError("Language not supported: %s" % lang)
            except RuntimeError as e:
                log.debug(str(e), exc_info=True)
                log.warning(str(e))

        self.lang_check = lang_check
        self.lang = lang.lower()

        # Read speed
        if slow:
            self.speed = Speed.SLOW
        else:
            self.speed = Speed.NORMAL

        # Pre-processors and tokenizer

tokenizer_func=Tokenizer([
                tokenizer_cases.tone_marks,
                tokenizer_cases.period_comma,
                tokenizer_cases.colon,
                tokenizer_cases.other_punctuation
            ]).run
    ):

        # Text
        assert text, 'No text to speak'
        self.text = text

        # Language
        if lang_check:
            try:
                langs = tts_langs()
                if lang.lower() not in langs:
                    raise ValueError("Language not supported: %s" % lang)
            except RuntimeError as e:
                log.debug(str(e), exc_info=True)
                log.warning(str(e))

        self.lang_check = lang_check
        self.lang = lang.lower()

        # Read speed
        if slow:
            self.speed = Speed.SLOW
        else:
            self.speed = Speed.NORMAL

        # Pre-processors and tokenizer

):

        # Debug
        for k, v in locals().items():
            if k == 'self':
                continue
            log.debug("%s: %s", k, v)

        # Text
        assert text, 'No text to speak'
        self.text = text

        # Language
        if lang_check:
            try:
                langs = tts_langs()
                if lang.lower() not in langs:
                    raise ValueError("Language not supported: %s" % lang)
            except RuntimeError as e:
                log.debug(str(e), exc_info=True)
                log.warning(str(e))

        self.lang_check = lang_check
        self.lang = lang.lower()

        # Read speed
        if slow:
            self.speed = Speed.SLOW
        else:
            self.speed = Speed.NORMAL

        # Pre-processors and tokenizer

def validate_lang(ctx, param, lang):
    """Validation callback for the  option.
    Ensures  is a supported language unless the  flag is set
    """
    if ctx.params['nocheck']:
        return lang

    try:
        if lang not in tts_langs():
            raise click.UsageError(
                "'%s' not in list of supported languages.\n"
                "Use --all to list languages or "
                "add --nocheck to disable language check." % lang)
        else:
            # The language is valid.
            # No need to let gTTS re-validate.
            ctx.params['nocheck'] = True
    except RuntimeError as e:
        # Only case where the  flag can be False
        # Non-fatal. gTTS will try to re-validate.
        log.debug(str(e), exc_info=True)

    return lang