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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def save(self, label='default', path=None):
 """Save the current connection configuration to a file. This method is thread safe. :param label: A string. An identifier for the current configuration. This allows multiple configurations with unique labels to be saved in a single file. If a configuration identified by ``label`` already exists in the destination configuration file, it is replaced. :param path: A string. The configuration file to be manipulated. By default, an XDG-compliant configuration file is used. A configuration file is created if one does not exist already. :returns: ``None`` """

        # What will we write out?
        cfg = vars(self)
        if 'version' in cfg:  # pragma: no cover
            cfg['version'] = str(cfg['version'])

        # Where is the file we're writing to?
        if path is None:
            path = join(
                BaseDirectory.save_config_path(self._xdg_config_dir),
                self._xdg_config_file
            )
        self._file_lock.acquire()

        try:
            # Either read an existing config or make an empty one. Then update
            # the config and write it out.
            try:
                with open(path) as config_file:
                    config = json.load(config_file)
            except IOError:  # pragma: no cover
                config = {}
            config[label] = cfg
            with open(path, 'w') as config_file:
                json.dump(config, config_file)
        finally:
            self._file_lock.release()