switch circle modes with left

def/Object.d.lua

@@ -21,4 +21,9 @@ function Object:extend() end
 ---@param mixin table
 function Object:implement(mixin) end
 
+---Checks if object is of a specific type
+---@param object Object
+---@return boolean
+function Object:is(object) end
+
 return Object

main.lua

@@ -23,6 +23,7 @@ Circle = require 'obj/game/Circle'
 function love.load()
     -- screen setup
     love.graphics.setDefaultFilter("nearest")
+    love.graphics.setLineStyle("rough")
     resize(2)
 
     ---@type Room|nil

rooms/Stage.lua

@@ -24,6 +24,15 @@ function Stage:update(dt)
         end
     end
 
+    if input:pressed('left') then
+        for _, game_object in ipairs(self.area.game_objects) do
+            if game_object:is(Circle) then
+                ---@cast game_object Circle
+                if game_object.mode == "fill" then game_object.mode = "line" else game_object.mode = "fill" end
+            end
+        end
+    end
+
     self.timer:update(dt)
 end