code: def root():
      
      response = {
          "links": {
              "message": "Welcome to the SIP Processing Controller Interface",
              "items": [
                  {"href": "{}health".format(request.url)},
                  {"href": "{}subarrays".format(request.url)},
                  {"href": "{}scheduling_blocks".format(request.url)},
                  {"href": "{}processing_blocks".format(request.url)}
              ]
          }
      }
      return response, HTTPStatus.OK
docs: Placeholder root url for the PCI.
  
      Ideally this should never be called!