Method thread_id

src/backward.h:767–767

    size_t load_here(size_t = 0) { return 0; }
    size_t load_from(void*, size_t = 0, void* = nullptr, void* = nullptr) { return 0; }
    size_t thread_id() const { return 0; }
    void skip_n_firsts(size_t) {}
};