code: def randombytes(n):
      
      # Use /dev/urandom if it is available.  Fall back to random module
      # if not.  It might be worthwhile to extend this function to use
      # other platform-specific mechanisms for getting random bytes.
      if os.path.exists("/dev/urandom"):
          f = open("/dev/urandom")
          s = f.read(n)
          f.close()
          return s
      else:
          L = [chr(random.randrange(0, 256)) for i in range(n)]
          return "".join(L)
docs: Return n random bytes.