class_docstr: Test ability to marshall multiselect protos.
docstr: Test that it casts options to string.
docstr_tok: ["Test","that","it","casts","options","to","string","."]
code: def test_cast_options_to_string(self):
      """Test that it casts options to string."""
      arg_options = ["some str", 123, None, {}]
      proto_options = ["some str", "123", "None", "{}"]
  
      st.multiselect("the label", arg_options, default=None)
  
      c = self.get_delta_from_queue().new_element.multiselect
      self.assertEqual(c.label, "the label")
      self.assertListEqual(c.default[:], [2])
      self.assertEqual(c.options, proto_options)
  
imports: from unittest.mock import MagicMock, patch
  import numpy
  import pandas
  import pytest
  from parameterized import parameterized
  import streamlit
  from streamlit.elements.widgets.multiselect import _get_default_count, _get_over_max_options_message
  from streamlit.errors import StreamlitAPIException
  from streamlit.proto.LabelVisibilityMessage_pb2 import LabelVisibilityMessage
  from streamlit.testing.v1.app_test import AppTest
  from streamlit.testing.v1.util import patch_config_options
  from tests.delta_generator_test_case import DeltaGeneratorTestCase
label_desc: Use image node_id 4 for calling the Multiselectbox obj's underlying member method code with example usage: obj.test_cast_options_to_string() without return types