code: def test_custom_input_registry(self):
      config = AlgorithmConfig().offline_data(input_config={})
      ioctx = IOContext(self.test_dir, config, 0, None)
  
      class CustomInputReader(InputReader):
          def __init__(self, ioctx: IOContext):
              self.ioctx = ioctx
  
          def next(self):
              return 0
  
      def input_creator(ioctx: IOContext):
          return ShuffledInput(CustomInputReader(ioctx))
  
      register_input("custom_input", input_creator)
      self.assertTrue(registry_contains_input("custom_input"))
      creator = registry_get_input("custom_input")
      self.assertIsNotNone(creator)
      reader = creator(ioctx)
      self.assertIsInstance(reader, ShuffledInput)
      self.assertEqual(reader.next(), 0)
      self.assertEqual(ioctx.log_dir, self.test_dir)
      self.assertEqual(ioctx.config, config)
      self.assertEqual(ioctx.worker_index, 0)
      self.assertIsNone(ioctx.worker)
      self.assertEqual(ioctx.input_config, {})
  
imports: import glob
  import json
  import numpy
  import os
  import random
  import shutil
  import tempfile
  import unittest
  import ray
  from ray.tune.registry import register_env, register_input, registry_get_input, registry_contains_input
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.algorithms.pg import PGConfig
  from ray.rllib.algorithms.ppo import PPOConfig
  from ray.rllib.examples.env.multi_agent import MultiAgentCartPole
  from ray.rllib.offline import IOContext, JsonWriter, JsonReader, InputReader, ShuffledInput, DatasetWriter
  from ray.rllib.offline.json_reader import from_json_data
  from ray.rllib.offline.json_writer import _to_json_dict, _to_json
  from ray.rllib.policy.sample_batch import SampleBatch, convert_ma_batch_to_sample_batch
  from ray.rllib.utils.test_utils import framework_iterator
label_desc: Use image node_id 11 for calling the JsonIOTest obj's underlying member method code with example usage: obj.test_custom_input_registry() and returns: ShuffledInput, int