code: def test_docstring_preservation(self):
      @tff.utils.dataclass
      class Coords:
          """A coordinate grid."""
  
          x: tf.Tensor
          y: tf.Tensor
  
      self.assertEqual(Coords.__doc__, "A coordinate grid.")
  
imports: import tensorflow.compat.v2
  import tf_quant_finance
  from tensorflow.python.framework import test_util
label_desc: Use image node_id 2 for calling the DataclassTest obj's underlying member method code with example usage: obj.test_docstring_preservation() without return types