class_docstr: Tests for every flavor of form/deltagenerator association.
class_docstr_tok: ["Tests","for","every","flavor","of","form\/deltagenerator","association","."]
docstr: Return the form ID for the last checkbox delta that was enqueued.
code: def _get_last_checkbox_form_id(self) -> str:
      """Return the form ID for the last checkbox delta that was enqueued."""
      last_delta = self.get_delta_from_queue()
      self.assertIsNotNone(last_delta)
      self.assertEqual("new_element", last_delta.WhichOneof("type"))
      self.assertEqual(
          "checkbox", last_delta.new_element.WhichOneof("type")
      )
      return last_delta.new_element.checkbox.form_id
  
imports: from unittest.mock import MagicMock, patch
  import streamlit
  from streamlit.errors import StreamlitAPIException
  from streamlit.runtime.state.session_state import RegisterWidgetResult
  from tests.delta_generator_test_case import DeltaGeneratorTestCase
label_desc: Use image node_id 1 for calling the FormAssociationTest obj's underlying member method code with example usage: obj._get_last_checkbox_form_id() and returns: last_delta