Callback method for received events.NewMessage

async def message_handler(self, event):
        """Callback method for received events.NewMessage"""

        # Note that message_handler is called when a Telegram update occurs
        # and an event is created. Telegram may not always send information
        # about the ``.sender`` or the ``.chat``, so if you *really* want it
        # you should use ``get_chat()`` and ``get_sender()`` while working
        # with events. Since they are methods, you know they may make an API
        # call, which can be expensive.
        chat = await event.get_chat()
        if event.is_group:
            if event.out:
                sprint('>> sent "{}" to chat {}'.format(
                    event.text, get_display_name(chat)
                ))
            else:
                sprint('<< {} @ {} sent "{}"'.format(
                    get_display_name(await event.get_sender()),
                    get_display_name(chat),
                    event.text
                ))
        else:
            if event.out:
                sprint('>> "{}" to user {}'.format(
                    event.text, get_display_name(chat)
                ))
            else:
                sprint('<< {} sent "{}"'.format(
                    get_display_name(chat), event.text
                ))