def METHOD_NAME(line: str) -> str:
    """Convert a string into a snake_cased string."""
    # replace non-alphanumeric characters with spaces in the reversed line
    subbed = re.sub(r"[^\w]|_", " ", line[::-1])
    # apply the regex on the reversed string
    words = REV_WORD_BOUND_PAT.split(subbed)
    # filter spaces between words and snake_case and reverse again
    return "_".join([w.lower() for w in words if w.strip()])[::-1]