Function check

dlib/external/pybind11/include/pybind11/pytypes.h:295–295

    bool operator!=(const handle &h) const { return m_ptr != h.m_ptr; }
    PYBIND11_DEPRECATED("Use handle::operator bool() instead")
    bool check() const { return m_ptr != nullptr; }

protected:
    PyObject *m_ptr = nullptr;