code: func (c *Context) DeleteMessagesWithEventID(eventID string) (deleted int, err error) {
  	var messages []OutgoingMessage
  	f := bson.M{"botid": c.Bot().ID, "eventid": eventID}
  
  	//update MAX_MSGS_TO_UPDATE_WITH_EVENTID last bot messages
  	c.db.C("messages").Find(f).Sort("-_id").Limit(MaxMsgsToUpdateWithEventID).All(&messages)
  	for _, message := range messages {
  		err = c.DeleteMessage(&message)
  		if err != nil {
  			c.Log().WithError(err).WithField("eventid", eventID).Error("DeleteMessagesWithEventID")
  		} else {
  			deleted++
  		}
  	}
  	return deleted, err
  }
docs: // DeleteMessagesWithEventID deletes the last MaxMsgsToUpdateWithEventID messages' text and inline keyboard with the corresponding eventID in ALL chats