def METHOD_NAME():
    sel = alt.selection_point(empty=False)
    c = (
        alt.Chart()
        .mark_point()
        .encode(size=alt.condition(sel, alt.value(100), alt.value(10)))
        .add_params(sel)
    )
    dct = c.to_dict()
    param_name = sel.param.name
    cond = dct["encoding"]["size"]["condition"]
    assert cond["value"] == 100
    assert cond["param"] == param_name
    # The else condition
    assert dct["encoding"]["size"]["value"] == 10