graph_state->system_state = new_state->system_state;
XBT_DEBUG("Snapshot %p of visited state %d (exploration stack state %d)",
new_state->system_state.get(), new_state->num, graph_state->num);
graph_state->system_state = new_state->system_state;
XBT_DEBUG("Snapshot %p of visited state %d (exploration stack state %d)",
new_state->system_state.get(), new_state->num, graph_state->num);