def make_training_sample(relev_articles, irrel_articles):
    """
    Builds the training sample
    Args:
        relev_articles: a list of relevant articles
        irrel_articles: a list of irrelevant articles
    """
    all_articles = relev_articles + irrel_articles
    training_sample = ""
    for article in all_articles:
        target, content = article
        training_sample += f"{target}\t{content}\n"
    return training_sample