def parse_output(self, data, sep='\n'):
        """
        Parse user command output

        :param data: output data list like, [b'data', b'data']
        :param sep:  line separator
        :return: output unicode data
        """
        output = []

        for d in data:
            self.stream.feed(d)
        for line in self.screen.display:
            if line.strip():
                output.append(line)
        self.screen.reset()
        return sep.join(output[0:-1])