code: def on_service_modify(self, svc_ref, old_properties):
          
          with self._lock:
              if self.reference is None:
                  # A previously registered service now matches our filter
                  self.on_service_arrival(svc_ref)
              elif svc_ref is self.reference:
                  # Notify the property modification
                  self._ipopo_instance.update(
                      self, self._value, svc_ref, old_properties
                  )
docs: Called when a service has been modified in the framework
  
          :param svc_ref: A service reference
          :param old_properties: Previous properties values