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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 readCfgJson(cls, working_path):
 """Read cmWalk configuration data of a working directory from a json file. :param working_path: working path for reading the configuration data. :return: the configuration data represented in a json object, None if the configuration files does not exist. """


        cfg_json_filename = os.path.join(working_path, cls.CFG_JSON_FILENAME)
        if os.path.isfile(cfg_json_filename):
            with open(cfg_json_filename) as json_file:
                cfg = json.load(json_file)
                return cfg
        return None