code: def test_dtype_for_string_types():
      assert feature.dtype_from_str("str") == np.object_
      assert feature.dtype_from_str("string") == np.object_
      assert feature.dtype_to_str(np.str_) == "string"
      assert feature.dtype_to_str(np.object_) == "string"
      assert feature.dtype_to_str(tf.string) == "string"
  
imports: import numpy
  import pytest
  import tensorflow
  from tensorflow_datasets.core.features import feature
  from tensorflow_datasets.core.features import image_feature
  from tensorflow_datasets.core.proto import feature_pb2
label_desc: Use image node_id 11 for calling a global function with example usage: test_dtype_for_string_types() without return types