def to_bulk(a, size=100):
    """Transform a list into list of list. Each element of the new list is a
    list with size=100 (except the last one).
    """
    r = []
    qt, rm = divmod(len(a), size)
    i = -1
    for i in range(qt):
        r.append(a[i * size:(i + 1) * size])
    if rm != 0:
        r.append(a[(i + 1) * size:])
    return r