code: def _set_token(self):
          
          try:
              self.token = os.environ['CERBERUS_TOKEN']
              if self.verbose:
                  print("Overriding Cerberus token with environment variable.", file=sys.stderr)
              logger.info("Overriding Cerberus token with environment variable.")
              return
          except:
              pass
          if self.username:
              ua = UserAuth(self.cerberus_url, self.username, self.password)
              self.token = ua.get_token()
          else:
              awsa = AWSAuth(self.cerberus_url, region=self.region, aws_session=self.aws_session, verbose=self.verbose)
              self.token = awsa.get_token()
docs: Set the Cerberus token based on auth type