Method get_i_with_pmfn

test/exec/test_function.cpp:222–225

    }

    exec::function<int(impl const *) noexcept> get_i_with_pmfn() const noexcept
    {
      return exec::function<int(impl const *) noexcept>(this, &impl::just_i);
    }

    exec::function<int() noexcept> get_i_virtually() const noexcept override
    {