fan.loop(startup:function?)start the event loop, can pass startup function or nothing.
fan.loopbreak()break the event loop, make sure call this api after all the daemon service(fifo, tcpd.bind, udpd.bind, httpd.bind) has been garbage collected.
fan.sleep(sec:number)sleep for any seconds, e.g. 0.1 or 10
fan.data2hex(data:string)convert binary data to hex string.
fan.hex2data(data:string)convert hex string to binary data.
fan.gettime()return 2 integer values, sec, usec