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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 _update_resourcescenario(scenario, resource_scenario, dataset=None, new=False, user_id=None, source=None):
 """ Insert or Update the value of a resource's attribute by first getting the resource, then parsing the input data, then assigning the value. returns a ResourceScenario object. """

    if scenario is None:
        scenario = db.DBSession.query(Scenario).filter(Scenario.id==1).one()

    ra_id = resource_scenario.resource_attr_id

    log.debug("Assigning resource attribute: %s",ra_id)
    try:
        r_scen_i = db.DBSession.query(ResourceScenario).filter(
                        ResourceScenario.scenario_id==scenario.id,
                        ResourceScenario.resource_attr_id==ra_id).one()
    except NoResultFound as e:
        log.info("Creating new RS")
        r_scen_i = ResourceScenario()
        r_scen_i.resource_attr_id = resource_scenario.resource_attr_id
        r_scen_i.scenario_id      = scenario.id
        r_scen_i.scenario = scenario

        db.DBSession.add(r_scen_i)


    if scenario.locked == 'Y':
        log.info("Scenario %s is locked",scenario.id)
        return r_scen_i


    if dataset is not None:
        r_scen_i.dataset = dataset

        return r_scen_i

    dataset = resource_scenario.dataset

    value = dataset.parse_value()

    log.info("Assigning %s to resource attribute: %s", value, ra_id)

    if value is None:
        log.info("Cannot set data on resource attribute %s",ra_id)
        return None

    metadata = dataset.get_metadata_as_dict(source=source, user_id=user_id)
    data_unit_id = dataset.unit_id

    data_hash = dataset.get_hash(value, metadata)

    assign_value(r_scen_i,
                 dataset.type.lower(),
                 value,
                 data_unit_id,
                 dataset.name,
                 metadata=metadata,
                 data_hash=data_hash,
                 user_id=user_id,
                 source=source)
    return r_scen_i