constexpr unsigned MPI_REQ_NON_PERSISTENT = 0x2;
constexpr unsigned MPI_REQ_SEND = 0x4;
constexpr unsigned MPI_REQ_RECV = 0x8;
constexpr unsigned MPI_REQ_NON_PERSISTENT = 0x2;
constexpr unsigned MPI_REQ_SEND = 0x4;
constexpr unsigned MPI_REQ_RECV = 0x8;