def METHOD_NAME(what):
    if len(what) == 0:
        raise dns.exception.FormError
    if what[0] == b"-"[0] or what[0] == b"+"[0]:
        what = what[1:]
    if what.isdigit():
        return
    try:
        (left, right) = what.split(b".")
    except ValueError:
        raise dns.exception.FormError
    if left == b"" and right == b"":
        raise dns.exception.FormError
    if not left == b"" and not left.decode().isdigit():
        raise dns.exception.FormError
    if not right == b"" and not right.decode().isdigit():
        raise dns.exception.FormError