code: def prepare_context(pipeline, context_in_string, context):
      
      logger.debug("starting")
  
      parsed_context = get_parsed_context(
          pipeline=pipeline,
          context_in_string=context_in_string)
  
      context.update(parsed_context)
  
      logger.debug("done")
docs: Prepare context for pipeline run.
  
      Args:
          pipeline: dict. Dictionary representing the pipeline.
          context_in_string: string. Argument string used to initialize context.
          context: pypyr.context.Context. Merge any new context generated from
                   context_in_string into this context instance.
  
      Returns:
          None. The context instance to use for the pipeline run is contained
                in the context arg, it's not passed back as a function return.