docs: def open(self):
          """Open the connection with the device."""
          try:
              self.device.open()
          except ConnectTimeoutError as cte:
              raise ConnectionException(cte.msg)
          self.device.timeout = self.timeout
          self.device._conn._session.transport.set_keepalive(self.keepalive)
          if hasattr(self.device, "cu"):
              # make sure to remove the cu attr from previous session
              # ValueError: requested attribute name cu already exists
              del self.device.cu
          self.device.bind(cu=Config)
          if not self.lock_disable and self.session_config_lock:
              self._lock()