code: def _adjust_cwd(self, path):
          
          path = b(path)
          if self._cwd is None:
              return path
          if len(path) and path[0:1] == b_slash:
              # absolute path
              return path
          if self._cwd == b_slash:
              return self._cwd + path
          return self._cwd + b_slash + path
docs: Return an adjusted path if we're emulating a "current working
          directory" for the server.