code: def get_confirmation_key(self, tag='', timestamp=None):
          
          return generate_confirmation_key(b64decode(self.identity_secret), tag,
                                           self.get_time() if timestamp is None else timestamp)
docs: :param tag: see :func:`generate_confirmation_key` for this value
          :type tag: str
          :param timestamp: time to use for code generation
          :type timestamp: int
          :return: trade confirmation key
          :rtype: str