code: def Sign(self, message, use_pss=False):
      
      precondition.AssertType(message, bytes)
  
      # TODO(amoser): This should use PSS by default at some point.
      if not use_pss:
        padding_algorithm = padding.PKCS1v15()
      else:
        padding_algorithm = padding.PSS(
            mgf=padding.MGF1(hashes.SHA256()), salt_length=padding.PSS.MAX_LENGTH)
  
      return self._value.sign(message, padding_algorithm, hashes.SHA256())
docs: Sign a given message.