def METHOD_NAME():
    geo_mapper = GeoMapper()
    state_pop = geo_mapper.get_crosswalk("state_id", "pop")
    identity_smoother = SMOOTHERS[0]
    hundo_k = 100000
    test_df = pd.DataFrame({  
        'state': ['pa', 'wv'],
        'timestamp': [datetime(year=2020, month=1, day=1)]*2,
        'val': [15., 150.],})
    pa_pop = int(state_pop[state_pop.state_id == "pa"]["pop"].iloc[0])
    wv_pop = int(state_pop[state_pop.state_id == "wv"]["pop"].iloc[0])
    pd.testing.assert_frame_equal(
        transform_signal(
            CONFIRMED_PROP,
            identity_smoother,
            'state',
            test_df.copy(),
            geo_mapper),
        pd.DataFrame({
            'geo_id': ['pa', 'wv'],
            'timestamp': [datetime(year=2020, month=1, day=1)]*2,
            'val': [15/pa_pop*hundo_k, 150/wv_pop*hundo_k],
            'se': [None]*2,
            'sample_size': [None]*2,}),
        check_dtype=False,
        check_like=True
    )
    pd.testing.assert_frame_equal(
        transform_signal(
            CONFIRMED_PROP,
            identity_smoother,
            'nation',
            test_df.copy(),
            geo_mapper),
        pd.DataFrame({
            'geo_id': ['us'],
            'timestamp': [datetime(year=2020, month=1, day=1)],
            'val': [165/(pa_pop+wv_pop)*hundo_k],
            'se': [None],
            'sample_size': [None],}),
        check_dtype=False,
        check_like=True
    )