message: Add most_specific_compatible_shape method in NoneTensorSpec. Otherwise when code will raise error when interleaving datasets with None in the flatten view.
diff: @@ -537,6 +537,12 @@ class NoneTensorSpec(type_spec.BatchableTypeSpec):
  def _to_legacy_output_classes(self):
  return self
  + def most_specific_compatible_shape(self, other):
  + if type(self) is not type(other):
  + raise ValueError("No TypeSpec is compatible with both %s and %s" %
  + (self, other))
  + return self
  +
  type_spec.register_type_spec_from_value_converter(type(None),
  NoneTensorSpec.from_value)
  