How to use the titlecase.__init__.Immutable function in titlecase

SMALL_FIRST = re.compile(r'^([%s]*)(%s)\b' % (PUNCT, SMALL), re.I)
SMALL_LAST = re.compile(r'\b(%s)[%s]?$' % (SMALL, PUNCT), re.I)
SUBPHRASE = re.compile(r'([:.;?!\-–‒—―][ ])(%s)' % SMALL)
APOS_SECOND = re.compile(r"^[dol]{1}['‘]{1}[a-z]+(?:['s]{2})?$", re.I)
UC_INITIALS = re.compile(r"^(?:[A-Z]{1}\.{1}|[A-Z]{1}\.{1}[A-Z]{1})+$")
MAC_MC = re.compile(r"^([Mm]c|MC)(\w.+)")


class Immutable(object):
    pass


text_type = unicode if sys.version_info < (3,) else str


class ImmutableString(text_type, Immutable):
    pass


class ImmutableBytes(bytes, Immutable):
    pass


def _mark_immutable(text):
    if isinstance(text, bytes):
        return ImmutableBytes(text)
    return ImmutableString(text)


def set_small_word_list(small=SMALL):
    global SMALL_WORDS
    global SMALL_FIRST

continue

            if all_caps:
                word = word.lower()

            # Just a normal word that needs to be capitalized
            tc_line.append(CAPFIRST.sub(lambda m: m.group(0).upper(), word))

        if small_first_last and tc_line:
            if not isinstance(tc_line[0], Immutable):
                tc_line[0] = SMALL_FIRST.sub(lambda m: '%s%s' % (
                    m.group(1),
                    m.group(2).capitalize()
                ), tc_line[0])

            if not isinstance(tc_line[-1], Immutable):
                tc_line[-1] = SMALL_LAST.sub(
                    lambda m: m.group(0).capitalize(), tc_line[-1]
                )

        result = " ".join(tc_line)

        result = SUBPHRASE.sub(lambda m: '%s%s' % (
            m.group(1),
            m.group(2).capitalize()
        ), result)

        processed.append(result)

    return "\n".join(processed)

UC_INITIALS = re.compile(r"^(?:[A-Z]{1}\.{1}|[A-Z]{1}\.{1}[A-Z]{1})+$")
MAC_MC = re.compile(r"^([Mm]c|MC)(\w.+)")


class Immutable(object):
    pass


text_type = unicode if sys.version_info < (3,) else str


class ImmutableString(text_type, Immutable):
    pass


class ImmutableBytes(bytes, Immutable):
    pass


def _mark_immutable(text):
    if isinstance(text, bytes):
        return ImmutableBytes(text)
    return ImmutableString(text)


def set_small_word_list(small=SMALL):
    global SMALL_WORDS
    global SMALL_FIRST
    global SMALL_LAST
    global SUBPHRASE
    SMALL_WORDS = re.compile(r'^(%s)$' % small, re.I)
    SMALL_FIRST = re.compile(r'^([%s]*)(%s)\b' % (PUNCT, small), re.I)