docs: def d8hdisttostrm(np, p, src, dist, thresh, workingdir=None,
                        mpiexedir=None, exedir=None, log_file=None, runtime_file=None, hostfile=None):
          """Run D8 horizontal distance down to stream.
          """
          fname = TauDEM.func_name('d8hdisttostrm')
          return TauDEM.run(FileClass.get_executable_fullpath(fname, exedir),
                            {'-p': p, '-src': src},
                            workingdir,
                            {'-thresh': thresh},
                            {'-dist': dist},
                            {'mpipath': mpiexedir, 'hostfile': hostfile, 'n': np},
                            {'logfile': log_file, 'runtimefile': runtime_file})