code: def test_exception_builder(self):
      op = CreatePythonOperator(
          MainOpFunctionThatThrowsCustomErrorInBuilder, [], []
      )
      with self.assertRaisesRegex(
          CustomError, "This is an intentional exception in builder."
      ):
          workspace.RunOperatorOnce(op)
  
imports: from caffe2.python import core, workspace
  from caffe2.python.core import CreatePythonOperator
  import caffe2.python.hypothesis_test_util
  from hypothesis import given, settings
  import hypothesis.strategies
  import numpy
label_desc: Use image node_id 3 for calling the PythonOpTest obj's underlying member method code with example usage: obj.test_exception_builder() without return types