code: def test_validate_yaml_schema_raise_exception_null_text():
      domain = f"""
      version: "{LATEST_TRAINING_DATA_FORMAT_VERSION}"
      responses:
        utter_ask_email:
        - text: What is your email ID?
        utter_ask_name:
        - text: null
      """
      with pytest.raises(validation_utils.YamlValidationException) as e:
          validation_utils.validate_yaml_schema(
              domain, DOMAIN_SCHEMA_FILE
          )
  
      assert (
          "Missing 'text' or 'custom' key in response or null 'text' value in response."
          in str(e.value)
      )
  
imports: from typing import Text
  from threading import Thread
  import pytest
  from pep440_version_utils import Version
  from rasa.shared.exceptions import YamlException, SchemaValidationError
  import rasa.shared.utils.io
  import rasa.shared.utils.validation
  import rasa.utils.io
  import rasa.shared.nlu.training_data.schemas.data_schema
  from rasa.shared.constants import CONFIG_SCHEMA_FILE, DOMAIN_SCHEMA_FILE, LATEST_TRAINING_DATA_FORMAT_VERSION
  from rasa.shared.nlu.training_data.formats.rasa_yaml import NLU_SCHEMA_FILE
  from rasa.shared.utils.validation import KEY_TRAINING_DATA_FORMAT_VERSION
label_desc: Use image node_id 7 for calling a global function with example usage: test_validate_yaml_schema_raise_exception_null_text() without return types