code: def commandline(self, **mpiargs):
          
          cmd = self.MDRUN.commandline()
          if self.mpiexec:
              cmd = self.mpicommand(**mpiargs) + cmd
          return cmd
docs: Returns simple command line to invoke mdrun.
  
          If :attr:`mpiexec` is set then :meth:`mpicommand` provides the mpi
          launcher command that prefixes the actual ``mdrun`` invocation:
  
             :attr:`mpiexec` [*mpiargs*]  :attr:`mdrun` [*mdrun-args*]
  
          The *mdrun-args* are set on initializing the class. Override
          :meth:`mpicommand` to fit your system if the simple default
          OpenMP launcher is not appropriate.