import math


def msg_chop(long_msg):
    """
        Chops the message into 150-char blocks and prepends (XX/YY)
    Args:
        long_msg: the original, long message string

    Returns:
        msg_blocks: list where each element is a 150-char msg block
    """
    if len(long_msg) < 160:
        return [long_msg]  # it fits, nothing to do here
    else:
        block_size = 150  # allot 10 chars for prepended (XX/YY)
        block_num = int(math.ceil(len(long_msg) / float(block_size)))
        msg_blocks = []

        for i in range(0, block_num):
            start = i * block_size
            msg_blocks.append("(%s/%s) %s" % (
                i + 1, block_num, long_msg[start:start + block_size]))
        return msg_blocks