title: Slack API method to send "typing"
body: <p>I have a very slow bot, because it performs time-consuming operations behind every message response, and sometimes it is just annoying for a user to send a message and wait for 2–3 seconds until the response has come. I'd like to send "typing" event right away until the real message is ready. But I don't see such method in the Slack API reference. Does it even exist? Maybe I could use a workaround to achieve that? Has anybody solved a similar problem?</p>