code: def subject_id(self):
          
  
          if "subject" in self.message.keys():
              _subj = self.message.subject
              if "base_id" in _subj.keys() and _subj.base_id:
                  return _subj.base_id
              elif _subj.name_id:
                  return _subj.name_id
          else:
              if "base_id" in self.message.keys() and self.message.base_id:
                  return self.message.base_id
              elif self.message.name_id:
                  return self.message.name_id
              else:  # EncryptedID
                  pass
docs: The name of the subject can be in either of
          BaseID, NameID or EncryptedID
  
          :return: The identifier if there is one