message: Returned Engines are not passed by reference.
diff: @@ -203,24 +203,24 @@ The available modes are ``adios2::Mode::Read``, ``adios2::Mode::Write``, ``adios
  /** Signatures */
  /** Provide a new MPI communicator other than from ADIOS->IO->Engine */
  - adios2::Engine &adios2::IO::Open( const std::string &name,
  + adios2::Engine adios2::IO::Open(const std::string &name,
  const adios2::Mode mode,
  MPI_Comm mpiComm );
  /** Reuse the MPI communicator from ADIOS->IO->Engine \n or non-MPI serial mode */
  - adios2::Engine &adios2::IO::Open(const std::string &name,
  + adios2::Engine adios2::IO::Open(const std::string &name,
  const adios2::Mode mode);
  /** Examples */
  /** Engine derived class, spawned to start Write operations */
  - adios2::Engine& bpWriter = io.Open("myVector.bp", adios2::Mode::Write);
  + adios2::Engine bpWriter = io.Open("myVector.bp", adios2::Mode::Write);
  /** Engine derived class, spawned to start Read operations on rank 0 */
  if( rank == 0 )
  {
  - adios2::Engine& bpReader = io.Open("myVector.bp",
  + adios2::Engine bpReader = io.Open("myVector.bp",
  adios2::Mode::Read,
  MPI_COMM_SELF);
  }
  