How to perform side-effect inside of an epic in redux-observable?

In redux-observable, epics are accepting stream of actions and returning back new stream of actions. In my use-case I need to send analytics event after some action was dispatched and do nothing after.

With redux-saga, I can just listen that action using takeEvery, and perform a side-effect inside of a saga function:

function* saga() {
  yield takeEvery('SOME_ACTION', function*() {
    sendAnalytics();
  })
}

But how can I achieve the same with redux-observable? There is pretty much side effects, that are not requiring dispatching new actions, like initializing plugins, logging, setting cookies etc...

If it's an anti-pattern for both of these libraries, what solution should be used for these kinds of effects?