import 'dart:async';
import 'dart:io';

void main() async {
  for(int i = 0;i<10;i++)
  {
    async_func(((i%10 + 1) * 1000));
  }

  await sleep(15000);
}

Future pause(Duration d) => new Future.delayed(d);

Future sleep(int i) => new Future.delayed(Duration(milliseconds: i));


void async_func(int i) async {
  await sleep(i);
  var now = new DateTime.now();
  print("async_func ($i)\t($now)" );
}