code: def test_supervised_keys_from_proto():
      proto = text_format.Parse(
          text="""
    tuple: {
        items: [
          {
            dict: {
              dict: {
                key: "f2"
                value: { feature_key: "f2" }
              },
              dict: {
                key: "f1"
                value: { feature_key: "f1" }
              },
            }
          },
          {
            feature_key: "target"
          }
        ]
      }
    """,
          message=dataset_info_pb2.SupervisedKeys(),
      )
      supervised_keys = dataset_info._supervised_keys_from_proto(
          proto=proto
      )
      assert (
          str(supervised_keys) == "({'f1': 'f1', 'f2': 'f2'}, 'target')"
      )
  
imports: import json
  import os
  import pathlib
  import tempfile
  import time
  from typing import Union
  import numpy
  import pytest
  import tensorflow
  from tensorflow_datasets import testing
  from tensorflow_datasets.core import dataset_builder
  from tensorflow_datasets.core import dataset_info
  from tensorflow_datasets.core import features
  from tensorflow_datasets.core import file_adapters
  from tensorflow_datasets.core import naming
  from tensorflow_datasets.core import read_only_builder
  from tensorflow_datasets.core import splits
  from tensorflow_datasets.core import utils
  from tensorflow_datasets.core.proto import dataset_info_pb2
  from tensorflow_datasets.core.proto import feature_pb2
  from tensorflow_datasets.image_classification import mnist
  from tensorflow_datasets.testing.dummy_config_based_datasets.dummy_ds_1 import dummy_ds_1_dataset_builder
  from google.protobuf import text_format
label_desc: Use image node_id 5 for calling a global function with example usage: test_supervised_keys_from_proto() without return types