def fetch_output(self, clear=True):
        """Fetch data from the subprocess output pipes.

        An output file not set to a pipe returns an empty string.
        """
        outdata = self.stdout.fetch_data(clear) if self.stdout is not None else ''
        errdata = self.stderr.fetch_data(clear) if self.stderr is not None else ''
        return outdata, errdata
Fetch data from the subprocess output pipes.

        An output file not set to a pipe returns an empty string.
        
recipes/Python/576957_Asynchronous_subprocess_using/recipe-576957.py