\
        Display history.
            history             Display history.
            history clear       Clear history.
            history clearall    Clear history for all shells.

def _do_history(self, cmd, args):
        """\
        Display history.
            history             Display history.
            history clear       Clear history.
            history clearall    Clear history for all shells.
        """
        if args and args[0] == 'clear':
            readline.clear_history()
            readline.write_history_file(self.history_fname)
        elif args and args[0] == 'clearall':
            readline.clear_history()
            shutil.rmtree(self._temp_dir, ignore_errors = True)
            os.makedirs(os.path.join(self._temp_dir, 'history'))
        else:
            readline.write_history_file(self.history_fname)
            with open(self.history_fname, 'r', encoding = 'utf8') as f:
                self.stdout.write(f.read())