input: Write a python function to monitor the performance of a distributed system using the 'celery' library.
  assert monitor_performance(tasks=["task1", "task2"], nodes=["node1", "node2"])=={"task1": "node1", "task2": "node2"}
  assert monitor_performance(tasks=["task3"], nodes=["node3"])=={"task3": "node3"}
  assert monitor_performance(tasks=[], nodes=[])=={}
output: def monitor_performance(tasks, nodes):
      return dict(zip(tasks, nodes))