53     Optional opt = std::optional("test"s);  in TEST()  local
54     static_assert(std::is_same_v<decltype(opt), Optional<std::string>>);  in TEST()
56     ASSERT_TRUE(opt);  in TEST()
57     EXPECT_EQ(opt.value(), "test"s);  in TEST()
72     Optional opt = 'x';  in TEST()  local
73     EXPECT_EQ('z', opt.transform([](char& c) {  in TEST()
78     EXPECT_EQ('y', opt);  in TEST()
94     Optional opt = "food"s;  in TEST()  local
95     EXPECT_EQ(ftl::unit, opt.transform(ftl::unit_fn([](std::string& str) { str.pop_back(); })));  in TEST()
96     EXPECT_EQ(opt, "foo"s);  in TEST()
132     Optional opt = 'x';  in TEST()  local
133     EXPECT_EQ('z', opt.and_then([](char& c) {  in TEST()
138     EXPECT_EQ('y', opt);  in TEST()
172     const Optional opt = false;  in TEST()  local
173     EXPECT_EQ(false, opt.or_else([] { return Optional(true); }));  in TEST()
179     const Optional<int> opt;  in TEST()  local
180     EXPECT_EQ(123, opt.or_else([]() -> Optional<int> { return 123; }));  in TEST()