Stream IDs

[shenek]

Once extraction of JSONs is performed. You may want to "split" the output to a several substreams and perform
some operation only in some of the streams.

e.g. you want to extract groups and users into and convert the name of the user into lower case. Note that both users and groups contain same field "name".

So the extracted stream could look like:

stream1 {"name": ..., "uid": ...}
stream2 {"name": ..., "gid": ...}

And each further operation would have an option to choose the stream(s) .