:for j from=1 to=4 step=1 do={
   :for i from=2000 to=50 step=-400 do={
     :beep frequency=$i length=11ms;
     :delay 11ms;
   }
   :for i from=800 to=2000 step=400 do={
     :beep frequency=$i length=11ms;
     :delay 11ms;
   }
 }