old_contents: #!/usr/bin/env python
  import sys, time
  import math
  
  class Ball:
  	gravity = -3 # Dots per second squared
  
  	def __init__(self):
  		self.r = 255
  		self.g = 0
  		self.b = 0
  
  		self.x = 0
  		self.y = 0
  		self.vx = 0
  		self.vy = 0
  
  	def updateValues(self):
  		self.x += self.vx
  		self.y += self.vy
  		self.vy += gravity
  
  	def drawOnMatrix(self, ledMatrix):
  		ledMatrix.SetPixel(self.x, self.y, self.r, self.g, self.b)
new_contents: #!/usr/bin/env python
  import sys, time
  import math
  
  class Ball:
  	gravity = -3 # Dots per second squared
  
  	def __init__(self):
  		self.r = 255
  		self.g = 0
  		self.b = 0
  
  		self.x = 0
  		self.y = 0
  		self.vx = 0
  		self.vy = 0
  
  	def updateValues(self):
  		self.x += self.vx
  		self.y += self.vy
  		self.vy += Ball.gravity
  
  	def drawOnMatrix(self, ledMatrix):
  		ledMatrix.SetPixel(self.x, self.y, self.r, self.g, self.b)
subject: Use class variable properly