# File karel/tk_robot_world.rb, line 104
 def place_beepers(street, avenue, howMany=1, byRobot = false)
    @beepers.synchronize do
      if howMany == 0
        @@beeper_control.signal
        return
      end
      legal_corner(street, avenue)
      place = [street, avenue]
      sleep(@@delay / 400.0) if byRobot
      if howMany < 0
        @beepers[place] = INFINITY
        if window()
          $window.delete_beeper(place)
          $window.place_beeper(street, avenue, INFINITY)
        
        end
      @@beeper_control.signal
      return
      end
      inWorld = @beepers[place]
      toPlace = howMany + inWorld
      if window() and inWorld != INFINITY
        @beepers[place] = toPlace
        $window.delete_beeper(place) if inWorld > 0
        $window.place_beeper(street, avenue, toPlace)
      end
      @@beeper_control.signal
    end
  
  end