code: def style_sheet(self):
          
          if self._style_sheet is None:
              self._style_sheet = StyleSheetList(self._version, assistant_sid=self._solution['sid'], )
          return self._style_sheet
docs: Access the style_sheet
  
          :returns: twilio.rest.autopilot.v1.assistant.style_sheet.StyleSheetList
          :rtype: twilio.rest.autopilot.v1.assistant.style_sheet.StyleSheetList