docs: def freeze(self, no_etag=False):
          """Call this method if you want to make your response object ready for
          pickeling.  This buffers the generator if there is one.  This also
          sets the etag unless `no_etag` is set to `True`.
          """
          if not no_etag:
              self.add_etag()
          super(ETagResponseMixin, self).freeze()