Method use_count

tests/test_local_bindings.cpp:29–29

        std::shared_ptr<int> contents;
        int value() const { return contents ? *contents : -20251012; }
        long use_count() const { return contents.use_count(); }
    };
    py::class_<SharedKeepAlive>(m, "SharedKeepAlive")
        .def_property_readonly("value", &SharedKeepAlive::value)