fcn powers(m){ n:=0.0; while(1){vm.yield(n.pow(m).toInt()); n+=1} }
var squared=Utils.Generator(powers,2), cubed=Utils.Generator(powers,3);

fcn filtered(sg,cg){s:=sg.next(); c:=cg.next();
   while(1){
      if(s>c){c=cg.next(); continue;}
      else if(s<c) vm.yield(s);
      s=sg.next()
   }
}
var f=Utils.Generator(filtered,squared,cubed);
f.drop(20);
f.walk(10).println();