Sure “from_spec” but I mean where is it? vl.from_spec does not exist. Neither does vl.vega.from_spec no vl.vegalite.from_spec and I do not understand how this vl thing is plugged into observable notebooks. That is the real problem else I could just grep/read stuff.
Yet observable has some assembly thing with js. So we need to know how things map. Another example is config (above). Not sure where that goes in the vl assembly yet.