code: def send_error(self, status_code=500, **kwargs):
          
          if hasattr(super(SentryMixin, self), 'log_exception'):
              return super(SentryMixin, self).send_error(status_code, **kwargs)
          else:
              rv = super(SentryMixin, self).send_error(status_code, **kwargs)
              if 500 <= status_code <= 599:
                  self.captureException(exc_info=kwargs.get('exc_info'))
              return rv
docs: Override implementation to report all exceptions to sentry, even
          after self.flush() or self.finish() is called, for pre-v3.1 Tornado.