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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 _mod_aggregate(self, low, running, chunks):
        '''
        Execute the aggregation systems to runtime modify the low chunk
        '''
        agg_opt = self.functions['config.option']('state_aggregate')
        if 'aggregate' in low:
            agg_opt = low['aggregate']
        if agg_opt is True:
            agg_opt = [low['state']]
        elif not isinstance(agg_opt, list):
            return low
        if low['state'] in agg_opt and not low.get('__agg__'):
            agg_fun = '{0}.mod_aggregate'.format(low['state'])
            if agg_fun in self.states:
                try:
                    low = self.states[agg_fun](low, chunks, running)
                    low['__agg__'] = True
                except TypeError:
                    log.error('Failed to execute aggregate for state %s', low['state'])
        return low