class_docstr: Test ability to marshall multiselect protos.
docstr: Test that it can be called with placeholder params.
docstr_tok: ["Test","that","it","can","be","called","with","placeholder","params","."]
code: def test_placeholder(self):
      """Test that it can be called with placeholder params."""
      st.multiselect(
          "the label",
          ["Coffee", "Tea", "Water"],
          placeholder="Select your beverage",
      )
  
      c = self.get_delta_from_queue().new_element.multiselect
      self.assertEqual(c.placeholder, "Select your beverage")
  
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 22 for calling the Multiselectbox obj's underlying member method code with example usage: obj.test_placeholder() without return types