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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 servers(**kwargs):  # pylint: disable=unused-argument

    '''
    Returns a list of the configured NTP servers on the device.

    CLI Example:

    .. code-block:: bash

        salt '*' ntp.servers

    Example output:

    .. code-block:: python

        [
            '192.168.0.1',
            '172.17.17.1',
            '172.17.17.2',
            '2400:cb00:6:1024::c71b:840a'
        ]
    '''

    ntp_servers = salt.utils.napalm.call(
        napalm_device,  # pylint: disable=undefined-variable
        'get_ntp_servers',
        **{
        }
    )

    if not ntp_servers.get('result'):
        return ntp_servers

    ntp_servers_list = list(ntp_servers.get('out', {}).keys())

    ntp_servers['out'] = ntp_servers_list

    return ntp_servers