recursive json dumper using Python dataset

def super_dupper_json_dumper(obj, table_name=None):
    global connection # connectin is a "dataset" db connection -  http://dataset.readthedocs.org/en/latest/quickstart.html#exporting-data
    if isinstance(obj, list):
        return [super_dupper_json_dumper(item) for item in obj]

    elif isinstance(obj, dict):
        o2 = obj.copy()
        for key, value in o2.items():
            if isinstance(item, list):
                # adivinhar como voce vai ler essas referencias de volta
                # de volta no objeto fica como um exercício de casa
                # dica:  criar uma outra funcao de leitura disso - analoga a essa
                o2[key] = repr(super_dupper_json_dumper(o2))
            elif isinstance(value, dict):
                o2[key] = super_dupper_json_dumper(value, key)[1]
        id = connection[table_name].insert(o2)
        return table_name, id
    else:
        raise NotImplemented