code: def eval(self, command):
          'Blocking call, returns the value of the execution in JS'
          event = threading.Event()
          # TODO: Add event to server
          #job_id = str(id(command))
          import random
          job_id = str(random.random())
          server.EVALUATIONS[job_id] = event
  
          message = '?' + job_id + '=' + command
          logging.info(('message:', [message]))
          for listener in server.LISTENERS.get(self.path, []):
              logging.debug(('listener:', listener))
              listener.write_message(message)
  
          success = event.wait(timeout=30)
  
          if success:
              value_parser = server.RESULTS[job_id]
              del server.EVALUATIONS[job_id]
              del server.RESULTS[job_id]
              return value_parser()
          else:
              del server.EVALUATIONS[job_id]
              if job_id in server.RESULTS:
                  del server.RESULTS[job_id]
              raise IOError('Evaluation failed.'f eval(self, command):
          'Blocking call, returns the value of the execution in JS'
          event = threading.Event()
          # TODO: Add event to server
          #job_id = str(id(command))
          import random
          job_id = str(random.random())
          server.EVALUATIONS[job_id] = event
  
          message = '?' + job_id + '=' + command
          logging.info(('message:', [message]))
          for listener in server.LISTENERS.get(self.path, []):
              logging.debug(('listener:', listener))
              listener.write_message(message)
  
          success = event.wait(timeout=30)
  
          if success:
              value_parser = server.RESULTS[job_id]
              del server.EVALUATIONS[job_id]
              del server.RESULTS[job_id]
              return value_parser()
          else:
              del server.EVALUATIONS[job_id]
              if job_id in server.RESULTS:
                  del server.RESULTS[job_id]
              raise IOError('Evaluation failed.')
docs: Blocking call, returns the value of the execution in JS