def index_batch_iterator(batch_size, n_sents):
    """
    Return batch indices
    """

    n_batches = n_sents//batch_size
    if (n_sents % batch_size) != 0:
        n_batches += 1

    low = 0
    high = 0
    range_list = []
    for i in range(n_batches):
        high = low + batch_size
        if high > n_sents:
            high = n_sents
        range_list.append((low, high))
        low = high
    return range_list