code: def _get_value(self, evt):
          
          if evt.err:
              e = evt.errors[0]
              return "[%s] %s" % (e.reason, e.desc)
  
          if isinstance(evt, EventData):
              return "[%s] %s" % (
                  evt.attr_value.quality, str(evt.attr_value.value))
          elif isinstance(evt, AttrConfEventData):
              cfg = evt.attr_conf
              return "label='%s'; unit='%s'" % (cfg.label, cfg.unit)
          elif isinstance(evt, DataReadyEventData):
              return ""
          elif isinstance(evt, PipeEventData):
              return evt.pipe_value
          elif isinstance(evt, DevIntrChangeEventData):
              print("utils::_get_value()")
              return
docs: Internal usage only