docs: def _wait_for_output(self):
          """
          Check if output matches banner.
  
          .. warning::
              Waiting for I/O completion. It does not work on Windows. Sorry.
          """
          # Here we should get an empty list or list with a tuple [(fd, event)]
          # When we get list with a tuple we can use readline method on
          # the file descriptor.
          poll_result = self.poll_obj.poll(0)
  
          if poll_result:
              line = self.output().readline()
              if self._banner.match(line):
                  return True
  
          return False