Function keepAlive

keepAlive(this, since?): Promise<UserSilence[]>
Needs to be done periodically to reset chat activity timeout
Parameters
- this: API
- Optionalsince: {
  message?: number | Message;
  user_silence?: number | UserSilence;
  }
  UserSilences that are before that will not be returned!
  - Optionalmessage?: number | Message
  - Optionaluser_silence?: number | UserSilence
Returns Promise<UserSilence[]>
A list of recent silences

Scope
"chat.read"

Remarks
Every 30 seconds is a good idea
- Defined in chat.ts:200