Method set_exception

imperative/python/src/graph_rt.h:112–133

    }

    void set_exception(std::exception_ptr e) {
        if (e) {
            MGB_LOCK_GUARD(m_lock);
            if (m_read_ahead >= 0) {
                mgb_assert(m_read_ahead <= 1);
                if (m_drop_next) {
                    m_drop_next = false;
                } else {
                    m_promise.set_exception(e);
                }
                if (m_read_ahead == 1) {
                    m_promise = {};
                }
                --m_read_ahead;
            } else {
                mgb_assert(m_read_ahead == -1);
                // TODO: maybe exception should be ignored
                // if value was already set ?
                m_promise.set_exception(e);
            }
        }
    }
};

void init_graph_rt(pybind11::module m);