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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 refresh(self):
 """ Fetches all current network names from the client. """

        if not self._client:
            return
        current_volumes = self._client.volumes()['Volumes']
        self.clear()
        if current_volumes:
            self.update(vol['Name'] for vol in current_volumes)