def make_ranges(arr_len, threads):
    """Make number ranges for threading from a given length.
    arr_len -- Integer. The length of the data to be split.
    threads -- Integer. The number of chunks/threads you want to use.
    """
    x = int(arr_len/threads)
    # print("x is", x)
    range_list = []
    for i in range(threads + 2):
        if 1 < i < threads + 1:
            range_list.append(((i-1)*x + 1, i*x))
        elif i == 0:
            range_list.append((i, i+x))
        elif i == threads:
            range_list.append(((i-1)*x + 1, arr_len))
    # print(range_list)
    return range_list