how to test django views that use requests module get method?

I know how to write django test code. But I don't know how to test with views that inlcude requests.get code View code is like this.

class CertificateAPIView(APIView):
    permission_classes = [IsAuthenticated, IsOwner]

    def put(self, request):
        imp = request.data.get("imp")
        response = requests.get('another server')
        uid = response.get('uid')
        if uid == None:
            return Response(
                {"detail": ValidationError(_("Certification is failed"))},
                status=status.HTTP_400_BAD_REQUEST,
            )
        ... more condition branch logics.
        return ...  

imp value is automatically created by 'another server' that I am not managing. This code is related with another server response and check condition branch with response. But before getting response with imp vlue, we can't check whether response is error.