code: def getThroughput(self, instId: int) -> float:
          
          # We are using the instanceStarted time in the denominator instead of
          # a time interval. This is alright for now as all the instances on a
          # node are started at almost the same time.
          if instId not in self.instances.ids:
              return None
          perf_time = time.perf_counter()
          throughput = self.throughputs[instId].get_throughput(perf_time)
          return throughput
docs: Return the throughput of the specified instance.
  
          :param instId: the id of the protocol instance