code: def save(self, file_path):
          
          fp = open(file_path, 'wb')
          json.dump(self.to_dict(), fp)
          fp.close()
          os.chmod(file_path, 0600)
docs: Persist a Session Token to a file in JSON format.
  
          :type path: str
          :param path: The fully qualified path to the file where the
              the Session Token data should be written.  Any previous
              data in the file will be overwritten.  To help protect
              the credentials contained in the file, the permissions
              of the file will be set to readable/writable by owner only.