code: def make_module_to_builder_dict(datasets=None):
    
    # pylint: disable=g-long-lambda
    # dict to hold tfds->image->mnist->[builders]
    module_to_builder = collections.defaultdict(
        lambda: collections.defaultdict(
            lambda: collections.defaultdict(list)))
    # pylint: enable=g-long-lambda
  
    if datasets:
      builders = [tfds.builder(name) for name in datasets]
    else:
      builders = [
          tfds.builder(name)
          for name in tfds.list_builders()
          if name not in BUILDER_BLACKLIST
      ] + [tfds.builder("image_label_folder", dataset_name="image_label_folder")]
  
    for builder in builders:
      mod_name = builder.__class__.__module__
      modules = mod_name.split(".")
      if "testing" in modules:
        continue
  
      current_mod_ctr = module_to_builder
      for mod in modules:
        current_mod_ctr = current_mod_ctr[mod]
      current_mod_ctr.append(builder)
  
    module_to_builder = module_to_builder["tensorflow_datasets"]
    return module_to_builder
docs: Get all builders organized by module in nested dicts.