Calculate (micro) accuracy.
    Args:
        gold: A 1d array-like of gold labels
        pred: A 1d array-like of predicted labels (assuming abstain = 0)
        ignore_in_gold: A list of labels for which elements having that gold
            label will be ignored.
        ignore_in_pred: A list of labels for which elements having that pred
            label will be ignored.

    Returns:
        A float, the (micro) accuracy score

def accuracy_score(gold, pred, ignore_in_gold=[], ignore_in_pred=[]):
    """
    Calculate (micro) accuracy.
    Args:
        gold: A 1d array-like of gold labels
        pred: A 1d array-like of predicted labels (assuming abstain = 0)
        ignore_in_gold: A list of labels for which elements having that gold
            label will be ignored.
        ignore_in_pred: A list of labels for which elements having that pred
            label will be ignored.

    Returns:
        A float, the (micro) accuracy score
    """
    gold, pred = _preprocess(gold, pred, ignore_in_gold, ignore_in_pred)

    if len(gold) and len(pred):
        acc = np.sum(gold == pred) / len(gold)
    else:
        acc = 0

    return acc