Load data from the IMDB dataset.

def load_data(limit=0, split=0.8):
    """Load data from the IMDB dataset."""
    # Partition off part of the train data for evaluation
    train_data, _ = thinc.extra.datasets.imdb()
    random.shuffle(train_data)
    train_data = train_data[-limit:]
    texts, labels = zip(*train_data)
    cats = [{"POSITIVE": bool(y), "NEGATIVE": not bool(y)} for y in labels]
    split = int(len(train_data) * split)
    return (texts[:split], cats[:split]), (texts[split:], cats[split:])