class_docstr: Registry of dataset registries.
  
  Each namespace is associated with one or more registers. Those registers can
  be any type of register, e.g. code on Github or datasets stored somewhere.
  
  Attributes:
    namespace_config: config where to find the datasets of a namespace.
    registers_per_namespace: per namespace a list of registers it consists of.
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docstr: Loads the builder class for the given dataset.
  
  Arguments:
    name: the name and namespace of the dataset to load the builder class for.
  
  Returns:
    DatasetNotFoundError if data is not found.
docstr_tok: ["Loads","the","builder","class","for","the","given","dataset",".","Arguments",":","name",":","the","name","and","namespace","of","the","dataset","to","load","the","builder","class","for",".","Returns",":","DatasetNotFoundError","if","data","is","not","found","."]
code: def builder_cls(
      self,
      name: naming.DatasetName,
  ) -> Type[dataset_builder.DatasetBuilder]:
      """Loads the builder class for the given dataset.
  
      Arguments:
        name: the name and namespace of the dataset to load the builder class for.
  
      Returns:
        DatasetNotFoundError if data is not found.
      """
      registers = self._get_registers(name)
  
      # Typically there's only 1, so add special case so that more informative
      # exceptions are raised.
      if len(registers) == 1:
          return registers[0].builder_cls(name)
  
      # If this dataset has multiple registers, use the first that can be found.
      for register in registers:
          try:
              return register.builder_cls(name)
          except registered.DatasetNotFoundError:
              pass
  
      raise registered.DatasetNotFoundError(
          f"Namespace {name.namespace} found, "
          f"but could not load dataset {name.name}."
          f"{self._get_list_builders_context(name)}"
      )
  
imports: import dataclasses
  import difflib
  import functools
  import os
  from typing import Any, Iterable, List, Mapping, Type
  from absl import logging
  from etils import epath
  from tensorflow_datasets.core import dataset_builder
  from tensorflow_datasets.core import github_api
  from tensorflow_datasets.core import naming
  from tensorflow_datasets.core import registered
  from tensorflow_datasets.core import utils
  from tensorflow_datasets.core.community import register_base
  from tensorflow_datasets.core.community import register_package
  from tensorflow_datasets.core.community import register_path
  from tensorflow_datasets.core.utils import gcs_utils
  import toml
label_desc: Use image node_id 9 for calling the DatasetRegistry obj's underlying member method code with example usage: obj.builder_cls(name) and returns: registers, register