title: How to get rid of pygame surfaces?
body: <p>In the following code, there is not just <strong>one</strong> circle on the screen at any given point in time.
  I want to fix this to make it so that it looks like there is only one circle, instead of leaving a smudge trail where ever the mouse cursor has been.</p>
  
  <pre><code>import pygame,sys
  from pygame.locals import *
  pygame.init()
  
  screen = pygame.display.set_mode((640,400),0,32)
  
  radius = 25
  circle = pygame.Surface([radius*2]*2,SRCALPHA,32)
  circle = circle.convert_alpha()
  pygame.draw.circle(circle,(25,46,100),[radius]*2,radius)
  
  while True:
      for event in pygame.event.get():
          if event.type == QUIT:
              pygame.quit()
              sys.exit()
  
      screen.blit(circle,(pygame.mouse.get_pos()[0],100))
  
      pygame.display.update()
      pygame.time.delay(10)
  </code></pre>