Meltano

Hi guys, can you give us a quick tutorial on how the visitor design pattern is implemented, what does singledispatch do and @visit.register(dict). the --select behaviour is very nice, we cannot get it to work on most taps though so need to debug. I see the first rule is ! * . * which makes sense

in particular this is necessary because the select does not select schemas only streams:
```    select:
    - '*.*'
    schema:
      '*':
        selected: 'true'```

Hi <@U06D0PUFLN4>! Taps in the wild do sometimes implement the singer catalog spec a bit different. The spec  reserves `metadata` for selection (see <https://github.com/singer-io/getting-started/blob/master/docs/DISCOVERY_MODE.md#the-catalog|here>) and under normal circumstances you shouldn't need to add a `"selected": true` in the middle of `schema`.

Is that your case? that the taps expect to indicate selection in the `schema` and not in the `metadata`?

Is that your case? that the taps expect to indicate selection in he `schema` and not in the `metadata`? YES, you need CatalogNode.SCHEMA in meltano