code: def number_of_processing_tasks(client):
      return sum(len(v) for k, v in client.processing().items())
  
imports: from __future__ import annotations
  import random
  from concurrent.futures import FIRST_COMPLETED, FIRST_EXCEPTION, Future, TimeoutError, as_completed, wait
  from time import sleep
  import pytest
  from tlz import take
  from distributed.event import Event
  from distributed.metrics import time
  from distributed.utils import CancelledError
  from distributed.utils_test import inc, slowadd, slowinc, throws, varying
label_desc: Use image node_id 1 for calling a global function with example usage: number_of_processing_tasks(client) and returns: sum