code: def _read_stderr(self):
          '''Continuously read stderr for error messages.'''
          try:
              while self._process.returncode is None:
                  line = yield from self._process.stderr.readline()
  
                  if not line:
                      break
  
                  if self._stderr_callback:
                      yield from self._stderr_callback(line)
  
          except Exception:
              _logger.exception('Unhandled read stderr exception.')
              raisf _read_stderr(self):
          '''Continuously read stderr for error messages.'''
          try:
              while self._process.returncode is None:
                  line = yield from self._process.stderr.readline()
  
                  if not line:
                      break
  
                  if self._stderr_callback:
                      yield from self._stderr_callback(line)
  
          except Exception:
              _logger.exception('Unhandled read stderr exception.')
              raise
docs: Continuously read stderr for error messages.