guard protecting the princess in my python game

guard

class Girl(GameElement):
  IMAGE = "Girl"	
	SOLID = True

	def __init__(self):
		GameElement.__init__(self)
		self.last_move = 0
		self.velocity_y = 1
				
	def update(self, dt):
		self.last_move += dt
		if self.last_move > 0.30:
		
			if self.y == 9:
				self.velocity_y = -1
			elif self.y == 0:
				self.velocity_y = 1

			self.board.del_el(self.x, self.y)
			self.y += self.velocity_y