code: def test_arrlen(client):
      client.json().set("arr", Path.root_path(), [0, 1, 2, 3, 4])
      assert 5 == client.json().arrlen("arr", Path.root_path())
      assert 5 == client.json().arrlen("arr")
      assert client.json().arrlen("fakekey") is None
  
imports: import pytest
  import redis
  from redis import Redis, exceptions
  from redis.commands.json.decoders import decode_list, unstring
  from redis.commands.json.path import Path
  from .conftest import _get_client, assert_resp_response, skip_ifmodversion_lt
label_desc: Use image node_id 21 for calling a global function with example usage: test_arrlen(client) without return types