class_docstr: Model card field base class.
  
  This is an abstract class. All the model card fields should inherit this class
  and override the _proto_type property to the corresponding proto type. This
  abstract class provides methods `from_proto`, `merge_from_proto` and
  `to_proto` to convert the class from and to proto. The child class does not
  need to override this unless it needs some special process.
docstr: The proto type. Child class should overwrite this.
docstr_tok: ["The","proto","type",".","Child","class","should","overwrite","this","."]
code: def _proto_type(self):
      """The proto type. Child class should overwrite this."""
  
imports: import abc
  import dataclasses
  import json
  from textwrap import dedent
  from typing import Any, Dict, Type, TypeVar
  from warnings import warn
  from google.protobuf import descriptor, message
  from model_card_toolkit.utils import json_utils
label_desc: Use image node_id 2 for calling the BaseModelCardField obj's underlying member method code with example usage: obj._proto_type() without return types