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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 list_groups(refresh=False):
    '''
    Return a list of groups

    Args:

        refresh (bool):
            Refresh the info for all groups in ``__context__``. If False only
            the groups in ``__context__`` will be returned. If True, the
            ``__context__`` will be refreshed with current data and returned.
            Default is False

    Returns:
        list: A list of groups on the machine

    CLI Example:

    .. code-block:: bash

        salt '*' group.list_groups
    '''
    if 'group.list_groups' in __context__ and not refresh:
        return __context__['group.list_groups']

    results = _get_all_groups()

    ret = []

    for result in results:
        ret.append(result.Name)

    __context__['group.list_groups'] = ret

    return ret