code: def serialize(self, v: object) -> int | None:
      if v is None:
          return None
  
      return 0 if len(self.options) == 0 else index_(self.options, v)
  
imports: from __future__ import annotations
  from dataclasses import dataclass
  from textwrap import dedent
  from typing import TYPE_CHECKING, Any, Callable, Generic, Sequence, cast
  from streamlit.elements.form import current_form_id
  from streamlit.elements.utils import check_callback_rules, check_session_state_rules, get_label_visibility_proto_value, maybe_coerce_enum
  from streamlit.errors import StreamlitAPIException
  from streamlit.proto.Radio_pb2 import Radio
  from streamlit.runtime.metrics_util import gather_metrics
  from streamlit.runtime.scriptrunner import ScriptRunContext, get_script_run_ctx
  from streamlit.runtime.state import WidgetArgs, WidgetCallback, WidgetKwargs, register_widget
  from streamlit.runtime.state.common import compute_widget_id
  from streamlit.type_util import Key, LabelVisibility, OptionSequence, T, check_python_comparable, ensure_indexable, maybe_raise_label_warnings, to_key
  from streamlit.util import index_
label_desc: Use image node_id 1 for calling the RadioSerde obj's underlying member method code with example usage: obj.serialize(v) and returns: unknown, None