def _connector_classes_str_to_dict(classes_conf_str):
    """
    Input: 'foo:bar, baz'
    Result: {'foo': 'bar', 'baz': 'baz'}
    """
    if len(classes_conf_str) == 0:
        return {}
    classes_conf_dict = {}
    for cc in classes_conf_str.split(','):
        cc_t = cc.strip().split(':')
        if len(cc_t) == 1:
           classes_conf_dict[cc_t[0]] = cc_t[0]
        else:
           classes_conf_dict[cc_t[0]] = cc_t[1]
    return classes_conf_dict