docs: def d8distdowntostream(np, p, fel, src, dist, distancemethod, thresh, workingdir=None,
                             mpiexedir=None, exedir=None,
                             log_file=None, runtime_file=None, hostfile=None):
          """Run D8 distance down to stream by different method for distance.
          This function is extended from d8hdisttostrm by Liangjun.
  
          Please clone `TauDEM by lreis2415`_ and compile for this program.
  
          .. _TauDEM by lreis2415:
             https://github.com/lreis2415/TauDEM
          """
          fname = TauDEM.func_name('d8distdowntostream')
          return TauDEM.run(FileClass.get_executable_fullpath(fname, exedir),
                            {'-fel': fel, '-p': p, '-src': src},
                            workingdir,
                            {'-thresh': thresh, '-m': TauDEM.convertdistmethod(distancemethod)},
                            {'-dist': dist},
                            {'mpipath': mpiexedir, 'hostfile': hostfile, 'n': np},
                            {'logfile': log_file, 'runtimefile': runtime_file})