docs: def start(self):
          """
          Start process.
  
          :returns: itself
          :rtype: OutputExecutor
  
          .. note::
  
              Process will be considered started, when defined banner will appear
              in process output.
          """
          super(OutputExecutor, self).start()
  
          # get a polling object
          self.poll_obj = select.poll()
  
          # register a file descriptor
          # POLLIN because we will wait for data to read
          self.poll_obj.register(self.output(), select.POLLIN)
  
          try:
              self.wait_for(self._wait_for_output)
  
              # unregister the file descriptor and delete the polling object
              self.poll_obj.unregister(self.output())
          finally:
              del self.poll_obj
          return self