code: def save_existing_iam_env_vars(self):
          
          for i in ['AWS_ACCESS_KEY_ID', 'AWS_SECRET_ACCESS_KEY',
                    'AWS_SESSION_TOKEN']:
              if i in self.env_vars:
                  self.env_vars['OLD_' + i] = self.env_vars[i]
docs: Backup IAM environment variables for later restoration.