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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_running():
    '''
    Return a list of all running services, so far as systemd is concerned

    CLI Example:

    .. code-block:: bash

        salt '*' service.get_running
    '''
    ret = set()
    # Get running systemd units
    out = __salt__['cmd.run'](
        _systemctl_cmd('--full --no-legend --no-pager'),
        python_shell=False,
        ignore_retcode=True)
    for line in salt.utils.itertools.split(out, '\n'):
        try:
            comps = line.strip().split()
            fullname = comps[0]
            if len(comps) > 3:
                active_state = comps[3]
        except ValueError as exc:
            log.error(exc)
            continue
        else:
            if active_state != 'running':
                continue
        try:
            unit_name, unit_type = fullname.rsplit('.', 1)
        except ValueError:
            continue
        if unit_type in VALID_UNIT_TYPES:
            ret.add(unit_name if unit_type == 'service' else fullname)

    return sorted(ret)