code: def test_rest_exception_error_code_is_not_none():
      error_string = "something important."
      exc = RestException({"message": error_string})
      assert "None" not in error_string
      assert "None" not in str(exc)
      json.loads(exc.serialize_as_json())
  
imports: import json
  from mlflow.exceptions import ExecutionException, RestException
  from mlflow.protos.databricks_pb2 import RESOURCE_DOES_NOT_EXIST, ErrorCode
label_desc: Use image node_id 3 for calling a global function with example usage: test_rest_exception_error_code_is_not_none() without return types