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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 _str_subgroups(self):
 """ helper function to render subgroups as a string """

        if not self.subgroups:
            return ""
        return ['subGroups %s'
                % ' '.join(['%s=%s' % (k, v) for (k, v) in
                           self.subgroups.items()])]