compound seq fn: sleep

sleep:
    description:
        sleep[t] seq
        sleep t milliseconds, then return seq
        useful for the rare case your code is too fast
        In particular, it is useful in walking-ant-v2.sw3
        where it is useful to slow down the ant so you can actually see his walking
        Note, t is the minimum sleep time, depending on what your code is doing, it could take longer

    examples:

    see also:
        walking-ant-v2.sw3