def METHOD_NAME(_str: str, langid: str = "en") -> str:
    """
    Convert digits to corresponding words. Note this is a naive approach and could be replaced with text normalization.
    """
    if langid == "en":
        num_to_words = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]
        _str = _str.strip()
        words = _str.split()
        out_str = ""
        num_word = []
        for word in words:
            if word.isdigit():
                num = int(word)
                while num:
                    digit = num % 10
                    digit_word = num_to_words[digit]
                    num_word.append(digit_word)
                    num = int(num / 10)
                    if not (num):
                        num_str = ""
                        num_word = num_word[::-1]
                        for ele in num_word:
                            num_str += ele + " "
                        out_str += num_str + " "
                        num_word.clear()
            else:
                out_str += word + " "
        out_str = out_str.strip()
    else:
        raise ValueError(
            "Currently support basic num_to_words in English only. Please use Text Normalization to convert other languages!"
        )
    return out_str