[Boost-users] Looking for boost library for timer callback function

I have been looking for a timer callback function in any boost library. I saw something like below by searching on the web: bool set_timer(time_duration_t fireTime, boost::function); But it did not give me further clue about which library contains this function. I also saw a discussion on the web about using ASIO but the document did not let me complete understand it. Does anyone has info about which library has the function of Timer callback? Thanks, Fanz