def METHOD_NAME(self, policy_string):
    assert type(policy_string) == str, "invalid type for policy_string"
    parser = PolicyParser()        
    policy_obj = parser.parse(policy_string)
    _dictCount, _dictLabel = {}, {}
    parser.findDuplicates(policy_obj, _dictCount)
    for i in _dictCount.keys(): 
        if _dictCount[ i ] > 1: _dictLabel[ i ] = 0
    parser.labelDuplicates(policy_obj, _dictLabel)
    return policy_obj