class_docstr: Base object for pipeline variables
  
  PipelineVariable subclasses must implement the expr property. Its subclasses include:
  :class:`~sagemaker.workflow.parameters.Parameter`,
  :class:`~sagemaker.workflow.properties.Properties`,
  :class:`~sagemaker.workflow.functions.Join`,
  :class:`~sagemaker.workflow.functions.JsonGet`,
  :class:`~sagemaker.workflow.execution_variables.ExecutionVariable`.
  :class:`~sagemaker.workflow.step_outputs.StepOutput`.
docstr: List of steps that this variable is generated from.
docstr_tok: ["List","of","steps","that","this","variable","is","generated","from","."]
code: def _referenced_steps(self) -> List[Union["Step", str]]:
      """List of steps that this variable is generated from."""
  
imports: from __future__ import absolute_import
  import abc
  from enum import EnumMeta
  from typing import Any, Dict, List, Union, TYPE_CHECKING
label_desc: Use image node_id 8 for calling the PipelineVariable obj's underlying member method code with example usage: obj._referenced_steps() without return types