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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 _add_device_to_device_group(self, device):
        '''Add device to device service cluster group.

        :param device: bigip object -- device to add to group
        '''

        device_name = get_device_info(device).name
        dg = pollster(self._get_device_group)(device)
        dg.devices_s.devices.create(name=device_name, partition=self.partition)
        pollster(self._check_device_exists_in_device_group)(device_name)