def check_max_one_training_agent(configuration):
    """
    Checks if there is at most one agent set to be trained
    :param configuration: the object group to look at
    :return: if there is less than 2 defined agents with the "train_mode" argument
    """
    training_agent_count = 0
    for agent in configuration["agents"]:
        if "train_mode" in agent["arguments"] and agent["arguments"]["train_mode"] == "True":
            training_agent_count += 1
    return training_agent_count < 2