code: def to_string(cls, error_code):
          
          if error_code == cls.RTT_ERROR_CONTROL_BLOCK_NOT_FOUND:
              return 'The RTT Control Block has not yet been found (wait?)'
          return super(JLinkRTTErrors, cls).to_string(error_code)
docs: Returns the string message for the given error code.
  
          Args:
            cls (JLinkRTTErrors): the ``JLinkRTTErrors`` class
            error_code (int): error code to convert
  
          Returns:
            An error string corresponding to the error code.
  
          Raises:
            ValueError: if the error code is invalid.