code: def test_num_ivy_arrays_on_dev(
      *,
      num,
      on_device,
      backend_fw,
  ):
      with BackendHandler.update_backend(backend_fw) as ivy_backend:
          arrays = [
              ivy_backend.array(
                  np.random.uniform(size=2).tolist(), device=on_device
              )
              for _ in range(num)
          ]
          assert ivy_backend.num_ivy_arrays_on_dev(on_device) == num
          for item in arrays:
              del item
  
imports: import io
  import multiprocessing
  import os
  import re
  import shutil
  import sys
  import warnings
  import numpy
  import psutil
  import subprocess
  from hypothesis import strategies, assume
  import ivy
  import ivy_tests.test_ivy.helpers
  import ivy_tests.test_ivy.helpers.globals
  from ivy_tests.test_ivy.helpers import handle_test, BackendHandler
label_desc: Use image node_id 21 for calling a global function with example usage: test_num_ivy_arrays_on_dev() without return types