def get(self, request, identifier=None, *args, **kwargs):  # type: ignore[no-untyped-def]
        """
        USING THIS ENDPOINT WITH AN IDENTIFIER IS DEPRECATED.
        Please use `/identities/?identifier=<identifier>` instead.
        ---
        Note that when providing the `feature` query argument, this endpoint will
        return either a single object or a 404 (if the feature does not exist) rather
        than a list.
        """
        if identifier:
            return self._get_flags_response_with_identifier(request, identifier)  # type: ignore[no-untyped-call]

        if "feature" in request.GET:
            feature_states = get_environment_flags_list(
                environment=request.environment,
                feature_name=request.GET["feature"],
                additional_filters=self._additional_filters,
            )
            if len(feature_states) != 1:
                # TODO: what if more than one?
                return Response(
                    {"detail": "Given feature not found"},
                    status=status.HTTP_404_NOT_FOUND,
                )

            return Response(self.get_serializer(feature_states[0]).data)

        if settings.CACHE_FLAGS_SECONDS > 0:
            data = self._get_flags_from_cache(request.environment)  # type: ignore[no-untyped-call]
        else:
            data = self.get_serializer(
                get_environment_flags_list(
                    environment=request.environment,
                    additional_filters=self._additional_filters,
                ),
                many=True,
            ).data

        updated_at = self.request.environment.updated_at
        return Response(
            data,
            headers={FLAGSMITH_UPDATED_AT_HEADER: updated_at.timestamp()},
        )

        USING THIS ENDPOINT WITH AN IDENTIFIER IS DEPRECATED.
        Please use `/identities/?identifier=<identifier>` instead.
        ---
        Note that when providing the `feature` query argument, this endpoint will
        return either a single object or a 404 (if the feature does not exist) rather
        than a list.
        
api/features/views.py