function stable
Returns an Observable that mirrors the source Observable, but will call a specified function when the source terminates on complete or error.
finalize<T>(callback: () => void): MonoTypeOperatorFunction<T>| callback |   Function to be called when source terminates.  |  
MonoTypeOperatorFunction<T>: An Observable that mirrors the source, but will call the specified function on termination.
    © 2015–2018 Google, Inc., Netflix, Inc., Microsoft Corp. and contributors.
Code licensed under an Apache-2.0 License. Documentation licensed under CC BY 4.0.
    https://rxjs.dev/api/operators/finalize