===================================================================
--- original.js
+++ change.js
@@ -14,9 +14,9 @@
 	self.velocity = 0;
 	self.flap = function () {
 		self.velocity += self.lift;
 	};
-	self.update = function () {
+	self._update_migrated = function () {
 		self.velocity += self.gravity;
 		self.y += self.velocity;
 		if (self.y > 2732 - birdGraphics.height / 2) {
 			self.y = 2732 - birdGraphics.height / 2;
@@ -35,9 +35,9 @@
 		anchorX: 0.5,
 		anchorY: 0.5
 	});
 	self.speed = -2;
-	self.move = function () {
+	self._move_migrated = function () {
 		self.x += self.speed;
 	};
 });
 // Pipe class
@@ -134,14 +134,14 @@
 	if (currentTime - lastPipeTime > pipeInterval) {
 		addPipe();
 		lastPipeTime = currentTime;
 	}
-	bird.update();
+	bird._update_migrated();
 	updatePipes();
 	checkCollision();
 	// Update clouds
 	for (var i = clouds.length - 1; i >= 0; i--) {
-		clouds[i].move();
+		clouds[i]._move_migrated();
 		if (clouds[i].x < -200) {
 			clouds[i].x = 2048;
 			clouds[i].y = Math.random() * 2732;
 		}