How to use the dataflows.delete_fields function in dataflows

dict(x=3, y='c', xx=True),
    ]
    f = Flow(
        data,
        delete_fields(['x'])
    )
    results, dp, _ = f.results()
    for i in results[0]:
        assert list(i.keys()) == ['y']
    assert dp.descriptor['resources'][0]['schema']['fields'] == \
        [dict(name='y', type='string', format='default')]

    f = Flow(
        data,
        data2,
        delete_fields(['x+'])
    )
    results, dp, _ = f.results()
    for res in results:
        for i in res:
            assert list(i.keys()) == ['y']
    assert dp.descriptor['resources'][0]['schema']['fields'] == \
        [dict(name='y', type='string', format='default')]

def test_delete_field():
    from dataflows import delete_fields
    data2 = [
        dict(x=1, y='a', xx=True),
        dict(x=2, y='b', xx=True),
        dict(x=3, y='c', xx=True),
    ]
    f = Flow(
        data,
        delete_fields(['x'])
    )
    results, dp, _ = f.results()
    for i in results[0]:
        assert list(i.keys()) == ['y']
    assert dp.descriptor['resources'][0]['schema']['fields'] == \
        [dict(name='y', type='string', format='default')]

    f = Flow(
        data,
        data2,
        delete_fields(['x+'])
    )
    results, dp, _ = f.results()
    for res in results:
        for i in res:
            assert list(i.keys()) == ['y']

def test_delete_fields_regex():
    from dataflows import load, delete_fields
    flow = Flow(
        load('data/regex.csv'),
        delete_fields(['temperature (24h)'], regex=False),
    )
    data = flow.results()[0]
    assert data == [[
        {'city': 'london'},
        {'city': 'paris'},
        {'city': 'rome'},
    ]]

def flow(parameters):
    resources = parameters.get('resources')
    regex = parameters.get('regex', True)
    return Flow(
        delete_fields(
            parameters.get('fields', []),
            resources=resources,
            regex=regex,
        )

],
        sources= [
            {
              "name": "Our Airports",
              "path": "http://ourairports.com/data/",
              "title": "Our Airports"
            }
        ],
        readme=readme()
    ),
    add_computed_field([{
        "operation": "format",
        "target": "coordinates",
        "with": "{latitude_deg}, {longitude_deg}"
    }]),
    delete_fields(fields=[
        "id","longitude_deg","latitude_deg",
        "scheduled_service","home_link","wikipedia_link","keywords"
    ]),
    update_resource('airport-codes', **{'path':'data/airport-codes.csv'}),
    validate(),
    dump_to_path()
)


def flow(parameters, datapackage, resources, stats):
    return dialing_info_cldr


if __name__ == '__main__':
    dialing_info_cldr.process()

def flow(parameters):
    resources = parameters.get('resources')
    regex = parameters.get('regex', True)
    if 'types' in parameters:
        return Flow(
            *[
                set_type(name, resources=resources, regex=regex, **options)
                if options is not None else
                delete_fields([name], resources=resources)
                for name, options in parameters['types'].items()
            ]
        )
    else:
        return Flow(
            validate()
        )