self.error = bg_err

        self.inputstream = inputstream

    def __iter__(self):

        return self

    def __next__(self):

        if self.process:

            returncode = self.process.poll()

            if (returncode is not None # process has terminated

                and returncode != 0

            ): # and it failed

                getattr(self.output, 'stop', lambda: None)()

                self.error.stop()

                err = ''.join(self.error)

                raise EnvironmentError("Subprocess exited due to an error:\n" + err)

        return next(self.output)

    def throw(self, type, value=None, traceback=None):

        if getattr(self.output, 'length') or not getattr(self.output, 'done_reading'):

            raise type(value)

    def close(self):

        try:

        except:

            pass

        try:

            getattr(self.output, 'close', lambda: None)()

        except:

            pass

        try:

            self.error.close()

        except:

            pass

        try:

            os.close(self.inputstream)

        except:

            pass