code: def test_task_exists(self):
      dataset = (
          foz.load_zoo_dataset("quickstart", max_samples=20)
          .select_fields("ground_truth")
          .clone()
      )
  
      anno_key = "task_exists"
      results = dataset.annotate(
          anno_key,
          label_field="ground_truth",
          backend="cvat",
          task_size=1,
      )
  
      tasks_exist = []
      with results:
          api = results.connect_to_api()
          for task_id in results.task_ids:
              tasks_exist.append(api.task_exists(task_id))
  
      dataset.load_annotations(anno_key, cleanup=True)
  
      self.assertNotIn(False, tasks_exist)
  
      view = dataset.take(1)
  
      anno_key = "task_not_exists"
      results = view.annotate(
          anno_key,
          label_field="ground_truth",
          backend="cvat",
      )
  
      task_id = results.task_ids[0]
      with results:
          api = results.connect_to_api()
          api.delete_task(task_id)
          self.assertFalse(api.task_exists(task_id))
  
      dataset.load_annotations(anno_key, cleanup=True)
  
imports: from bson import ObjectId
  from collections import defaultdict
  import numpy
  import os
  import unittest
  import eta.core.utils
  import fiftyone
  import fiftyone.utils.cvat
  import fiftyone.zoo
  from fiftyone.core.expressions import ViewField
label_desc: Use image node_id 15 for calling the CVATTests obj's underlying member method code with example usage: obj.test_task_exists() without return types