start a new experiment

def create_experiment(args):
    '''start a new experiment'''
    config_file_name = ''.join(random.sample(string.ascii_letters + string.digits, 8))
    nni_config = Config(config_file_name)
    config_path = os.path.abspath(args.config)
    if not os.path.exists(config_path):
        print_error('Please set correct config path!')
        exit(1)
    experiment_config = get_yml_content(config_path)
    validate_all_content(experiment_config, config_path)

    nni_config.set_config('experimentConfig', experiment_config)
    launch_experiment(args, experiment_config, 'new', config_file_name)
    nni_config.set_config('restServerPort', args.port)