CommImplPtr iprobe(int type, const std::function<bool(void*, void*, CommImpl*)>& match_fun, void* data);
CommImplPtr find_matching_comm(CommImplType type, const std::function<bool(void*, void*, CommImpl*)>& match_fun,
void* this_user_data, const CommImplPtr& my_synchro, bool done, bool remove_matching);
CommImplPtr iprobe(int type, const std::function<bool(void*, void*, CommImpl*)>& match_fun, void* data);
CommImplPtr find_matching_comm(CommImplType type, const std::function<bool(void*, void*, CommImpl*)>& match_fun,
void* this_user_data, const CommImplPtr& my_synchro, bool done, bool remove_matching);