title: I keep getting an error when using a spritesheet in python
body: <p>I am getting 2 errors when trying to run my code, but there's probably more as this is my first time using spritesheets.
  The first error is that when calling for the spritesheet it gives me an error saying I am giving 4 argument when it needs only 3. I seem to only see 3 arguments though. The second error is a 'tuple' object is not callable for this line of code:<code>(-1*halfSpriteWidth,-1*spriteHeight),(-1*spriteWidth,-1*spriteHeight)])</code>. Could someone please help me figure this out.</p>
  
  <pre><code>class spritesheet:
      def __init__(filename,columns,rows):
          sheet = image.load(filename)
          totalCellCount = columns * rows
          rect = sheet.get_rect()
          spriteWidth = cellWidth = rect.width / columns
          spriteHeight = cellHeight = rect.height / rows
          halfSpriteWidth, halfSpriteHeight = cellCenter = (spriteWidth/2,spriteHeight/2)
          cells = list([(index % columns * spriteWidth, index / columns * spriteHeight,spriteWidth,spriteHeight)for index in range(totalCellCount)])
          handle = list([
              (0,0), (-1*halfSpriteWidth,0),(-1*spriteWidth,0),
              (0,-1*halfSpriteHeight),(-1*halfSpriteWidth,-1*halfSpriteHeight),
              (-1*spriteWidth,-1*halfSpriteHeight),(0,-1*spriteHeight)
              (-1*halfSpriteWidth,-1*spriteHeight),(-1*spriteWidth,-1*spriteHeight)])
          def draw(surface,cellIndex, x,y,handle = 0):
              surface.blit(self.sheet(x + handle[handle][0], y + handle[handle][1]),cells[cellIndex])
  
  player = spritesheet('player.png',4,4)
  centerHandle = 4
  index = 0
  </code></pre>