def split_string_at_suffix(s, numbers_into_suffix=False):
    """
    Split a string into two parts: a prefix and a suffix. Splitting is done from the end,
    so the split is done around the position of the last digit in the string
    (that means the prefix may include any character, mixing digits and chars).
    The flag 'numbers_into_suffix' determines whether the suffix consists of digits or non-digits.
    """
    if not s:
        return (s, '')
    pos = len(s)
    while pos and numbers_into_suffix == s[pos - 1].isdigit():
        pos -= 1
    return (s[:pos], s[pos:])