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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def Readdir(self, path, fh=None):
 """Updates the directory listing from the client. Args: path: The path to the directory to update. Client is inferred from this. fh: A file handler. Not used. Returns: A list of filenames. """

    if self.DataRefreshRequired(path):
      self._RunAndWaitForVFSFileUpdate(path)

    return super(GRRFuse, self).Readdir(path, fh=None)