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: Prompt the pipeline to convert the pipeline variable to String in runtime
docstr_tok: ["Prompt","the","pipeline","to","convert","the","pipeline","variable","to","String","in","runtime"]
code: def to_string(self):
      """Prompt the pipeline to convert the pipeline variable to String in runtime"""
      from sagemaker.workflow.functions import Join
  
      return Join(on="", values=[self])
  
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 5 for calling the PipelineVariable obj's underlying member method code with example usage: obj.to_string() and returns: Join