def test_custom_plural_function():
    pfunc = lambda n: n > 2
    assert mod.plur('book', 1, pfunc) == 'book'
    assert mod.plur('book', 2, pfunc) == 'book'
    assert mod.plur('book', 3, pfunc) == 'books'
def test_custom_convert_function():
    cfunc = lambda s, p: s + 'mi' if p else s
    assert mod.plur('book', 1, convert=cfunc) == 'book'
    assert mod.plur('book', 2, convert=cfunc) == 'bookmi'
def test_plur():
    assert mod.plur('book', 1) == 'book'
    assert mod.plur('book', 2) == 'books'