Set response output speech as plain text type.

        Args:
            text: str. Response speech used when type is 'PlainText'. Cannot exceed
                8,000 characters.

def set_speech_text(self, text):
        """Set response output speech as plain text type.

        Args:
            text: str. Response speech used when type is 'PlainText'. Cannot exceed
                8,000 characters.
        """
        self.response.outputSpeech.type = 'PlainText'
        self.response.outputSpeech.text = text