def METHOD_NAME(example_zpk_fs_tuple):
    fs = 0.1
    b = numpy.array([1, 0.2, 0.5])
    # this should be converted to ZPK form
    dform, dfilt = filter_design.convert_to_digital(b, fs)
    assert dform == 'ba'
    assert numpy.allclose(dfilt, signal.bilinear(b, [1], fs))