new_contents: #!/usr/bin/env python
  
  '''
  Run all the solutions for which we know the ansewr, and check them.
  '''
  
  import subprocess
  
  answer = { 1 : 233168,
             2 : 4613732,
             3 : 6857,
             4 : 906609,
             5 : 232792560,
             6 : 25164150,
             7 : 104743,
             8 : 40824,
            10 : 142913828922,
            11 : 70600674,
            12 : 76576500,
            13 : 5537376230,
            14 : 837799,
            15 : 137846528820
  }
  
  #import pdb; pdb.set_trace()
  
  for problem in answer.keys():
      filename = 'euler' + str(problem).zfill(3) + '.py'
      print "{} ...".format(filename),
      result = subprocess.check_output(['python',filename])
      result = int(result.strip())
      if result != answer[problem]:
          print "failed! Expected {}, got {}".format(answer[problem], result)
      else:
          print u'\u221a'
  
subject: add regression tests