validation for pos device - some changes in pos device models

apps/pos_device/pos/api/v1/viewsets/device.py

@@ -0,0 +1,8 @@
+from rest_framework import viewsets
+from rest_framework.response import Response
+
+
+class TestViewSet(viewsets.ModelViewSet):
+
+    def list(self, request, *args, **kwargs):
+        return Response("Hello from the outsiiiiiiiiide")  # noqa