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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 _clean_servers(self):
 """ Clean the list of running console servers """

        if len(self._telnet_servers) > 0:
            for telnet_server in self._telnet_servers:
                telnet_server.close()
                yield from telnet_server.wait_closed()
            self._telnet_servers = []