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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 get_all():
    '''
    Return all installed services.

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_all
    '''
    ret = []
    service = _cmd()
    for svc in __salt__['cmd.run']('{0} ls all'.format(service)).splitlines():
        ret.append(svc)
    return sorted(ret)