class_docstr: Cast the dataset shape to tf.string.
code: def transform(self, dataset):
      return dataset.map(data_utils.cast_to_string)
  
imports: import tensorflow
  from autokeras import analysers
  from autokeras import keras_layers
  from autokeras import preprocessors
  from autokeras.engine import preprocessor
  from autokeras.utils import data_utils
label_desc: Use image node_id 1 for calling the CastToString obj's underlying member method code with example usage: obj.transform(dataset) and returns: dataset