docs: def extract_message_value(self, name):
          ''' search message to find and extract a named value '''
          name += ":"
          assert(self._message)
          _start = self._message.find(name)
          if _start >= 0:
              _start += len(name) + 1
              _end = self._message.find("\n", _start)
              _value = self._message[_start:_end]
              return _value.strip()
  
          return None