data = pd.DataFrame({"a": list("CCCDDDEEE"), "b": [2, 7, 4, 1, 2, 6, 8, 4, 7]})
spec = alt.Chart(data).mark_point().encode(x="a", y="b")
chart = AltairChart(title="Scientific Proof")
chart.set_data(spec)

class SciChart(AltairChart):
    title = "Scientific Proofiness"

    def load(self):
        data = pd.DataFrame({"a": list("CCCDDDEEE"), "b": [2, 7, 4, 1, 2, 6, 8, 4, 10]})
        spec = alt.Chart(data).mark_point().encode(x="a", y="b")
        self.set_data(spec)