To load the config
    :param yml_file: the config file path
    :param conf: dict, to override global config
    :return: dict

def load_conf(yml_file, conf={}):
    """
    To load the config
    :param yml_file: the config file path
    :param conf: dict, to override global config
    :return: dict
    """
    with open(yml_file) as f:
        data = yaml.load(f)
        if conf:
            data.update(conf)
        return dictdot(data)