def add_writer(self, stream, isatty=None):
        self.writers.append(stream)
        isatty = stream.isatty() if (isatty is None) else isatty
        self._isatty = self._isatty and isatty
adds a stream to the list of writers
dataset/ETHPy150Open pydoit/doit/doit/action.py/Writer.add_writer