code: def versioned_workdir(self):
      
      versioned_workdir = os.path.join(self.workdir, self.implementation_version_slug())
      safe_mkdir(versioned_workdir)
      return versioned_workdir
docs: The Task.workdir suffixed with a fingerprint of the Task implementation version.
  
      When choosing whether to store values directly in `self.workdir` or below it in
      the directory returned by this property, you should generally prefer this value.
  
      :API: public