int dup(MPI_Comm* newcomm);
int dup_with_info(MPI_Info info, MPI_Comm* newcomm);
MPI_Group group();
MPI_Topology topo() { return topo_; }
int size();
int rank();
int dup(MPI_Comm* newcomm);
int dup_with_info(MPI_Info info, MPI_Comm* newcomm);
MPI_Group group();
MPI_Topology topo() { return topo_; }
int size();
int rank();