How to trigger side effect after subscribe to channel?

Hello. How i can achieve this right after I subscribe to trigger a callback function that will f.ex do a api-request to some endpoint?

So I have this like this:
` Subscription: {
myQuery: {
subscribe: ()=>pubsub.asyncIterator(channelId);,
resolve: (payload: myType) => {
return payload
},
},
},`

I would like right after I register/subscribe to channel to trigger it so somehow after
`pubsub.asyncIterator(channelId)` this line runs. I tried some hacky solution with setTimeout but that is not good one.

Start with the Subscription configuration and the pubsub.asyncIterator(channelId) entry point shown in the issue. Determine whether the library exposes a supported post-subscription callback or hook, and document the expected behavior and completion criteria; no file or test is identified in the report.

Written by the indexing model from the issue text.