Post a message on the screen with Messenger.
            Arguments:
                message: The message to display.
                duration: The time until the message vanishes. (Default: 2.55s)
                pause: If True, the program waits until the message completes.
                style: "info", "success", or "error".

            You can also post messages by using =>
                self.execute_script('Messenger().post("My Message")')

def post_message(self, message, duration=None, pause=True, style="info"):
        """ Post a message on the screen with Messenger.
            Arguments:
                message: The message to display.
                duration: The time until the message vanishes. (Default: 2.55s)
                pause: If True, the program waits until the message completes.
                style: "info", "success", or "error".

            You can also post messages by using =>
                self.execute_script('Messenger().post("My Message")')
        """
        if not duration:
            if not self.message_duration:
                duration = settings.DEFAULT_MESSAGE_DURATION
            else:
                duration = self.message_duration
        js_utils.post_message(
            self.driver, message, duration, style=style)
        if pause:
            duration = float(duration) + 0.15
            time.sleep(float(duration))