a> this is
the most important method to create side effects. It's especially not allowed to use Functor#map
to do side effects. Instead, use this method
</p></div><dl class="paramcmts block"><dt class="param">f</dt><dd class="cmt"><p>the method to call</p></dd><dt>returns</dt><dd class="cmt"><p>An object with which you can stop listening to the underlying Signal/event. When you call</p></dd></dl><dl class="attributes block"> <dt>Definition Classes</dt><dd><a href="ReactiveLibrary$$Observable.html" class="ex