class_docstr: Output for a callback step.
  
  Attributes:
      output_name (str): The output name
      output_type (CallbackOutputTypeEnum): The output type
class_docstr_tok: ["Output","for","a","callback","step",".","Attributes",":","output_name","(","str",")",":","The","output","name","output_type","(","CallbackOutputTypeEnum",")",":","The","output","type"]
docstr: The 'Get' expression dict for a `CallbackOutput`.
docstr_tok: ["The","'Get","'","expression","dict","for","a","`","CallbackOutput","`","."]
code: def expr(self, step_name) -> Dict[str, str]:
      """The 'Get' expression dict for a `CallbackOutput`."""
      return CallbackOutput._expr(self.output_name, step_name)
  
imports: from __future__ import absolute_import
  from typing import List, Dict, Union, Optional
  from enum import Enum
  import attr
  from sagemaker.workflow.entities import RequestType
  from sagemaker.workflow.properties import Properties
  from sagemaker.workflow.entities import DefaultEnumMeta
  from sagemaker.workflow.step_collections import StepCollection
  from sagemaker.workflow.steps import Step, StepTypeEnum, CacheConfig
label_desc: Use image node_id 2 for calling the CallbackOutput obj's underlying member method code with example usage: obj.expr(step_name) and returns: CallbackOutput