Allow to assign a new expression to a new viz variable when the layer has been loaded

[elenatorro]

It is not possible to create a new expression and the assign it to a variable once the layer has been loaded.

It would be great to be able to:

const viz = new carto.Viz(`
    color: ramp($addrtype, Bold)
`);

const layer = new carto.Layer('layer', source, viz);

layer.on('loaded', () => {
    viz.addVariable('myVariable', 'ramp($addrtype, Prism)`)
    viz.color.blendTo('@myVariable', 0);
});

[AdriSolid]

In love with 'addVariable' method 🙏

[elenatorro]

It's not in the roadmap at the moment, but I'll take this feedback into account 👀