code: def cd(self, dir_p):
          
          if not isinstance(dir_p, basestring):
              raise TypeError("dir_p can only be an instance of type basestring")
          progress = self._call("cd",
                       in_p=[dir_p])
          progress = IProgress(progress)
          return progress
docs: Change the current directory level.
  
          in dir_p of type str
              The name of the directory to go in.
  
          return progress of type :class:`IProgress`
              Progress object to track the operation completion.