Method sig

include/pybind11/pybind11.h:274–274

We have to repeat PYBIND11_READABLE_FUNCTION_SIGNATURE_EXPR in decltype() because C++11 doesn't allow functions to return `auto`. (We don't know the type because it's some variant of detail::descr with unknown N.)

    // know the type because it's some variant of detail::descr<N> with
    // unknown N.)
    static constexpr sig_type sig() { return PYBIND11_READABLE_FUNCTION_SIGNATURE_EXPR; }

public:
    static constexpr sig_type kSig = sig();