code: def _get_shoulds(options):
      
      if options.version == '2.0':
          return shoulds20.list_shoulds(options)
      else:
          return shoulds21.list_shoulds(options)
docs: Return the list of 'SHOULD' validators for the correct version of STIX.
  
      Args:
          options: ValidationOptions instance with validation options for this
              validation run, including the STIX spec version.