code: def test_len(self):
      v = self.client.load_balanced_view()
      ar = v.map_async(lambda x: x, list(range(10)))
      assert len(ar) == 10
      ar = v.apply_async(lambda x: x, list(range(10)))
      assert len(ar) == 1
      ar = self.client[:].apply_async(lambda x: x, list(range(10)))
      assert len(ar) == len(self.client.ids)
  
imports: import os
  import time
  from datetime import datetime
  import pytest
  from IPython.utils.io import capture_output
  import ipyparallel
  from ipyparallel import error
  from .clienttest import ClusterTestCase, raises_remote
label_desc: Use image node_id 15 for calling the TestAsyncResult obj's underlying member method code with example usage: obj.test_len() without return types