code: def get_plain_text_content(primary_text=None, secondary_text=None, tertiary_text=None):
      # type: (str, str, str) -> TextContent
      
      return get_text_content(
          primary_text=primary_text, primary_text_type=PLAIN_TEXT_TYPE,
          secondary_text=secondary_text, secondary_text_type=PLAIN_TEXT_TYPE,
          tertiary_text=tertiary_text, tertiary_text_type=PLAIN_TEXT_TYPE)
docs: Responsible for building plain text content object using
      ask-sdk-model in Alexa skills kit display interface.
      https://developer.amazon.com/docs/custom-skills/display-interface-reference.html#textcontent-object-specifications.
  
      :param primary_text: Text for primary_text field
      :type primary_text: (optional) str
      :param secondary_text: Text for secondary_text field
      :type secondary_text: (optional) str
      :param tertiary_text: Text for tertiary_text field
      :type tertiary_text: (optional) str
      :return: Text Content instance with primary, secondary and tertiary
          text set as Plain Text objects.
      :rtype: TextContent
      :raises: ValueError