docs: def addsuffix(subject, suffix, replace=False):
    """
    Adds the specified *suffix* to the *subject*. If *replace* is True, the
    old suffix will be removed first. If *suffix* is callable, it must accept
    exactly one argument and return a modified value.
    """
  
    if not suffix and not replace:
      return subject
    if replace:
      subject = rmvsuffix(subject)
    if suffix and callable(suffix):
      subject = suffix(subject)
    elif suffix:
      subject += suffix
    return subject