text: #!/usr/bin/env python3
  import sys
  tests = {}
  base = "difftest.out"
  f = open(base, 'r')
  lines = f.readlines()
  
  fails=[]
  gots = []
  wants = []
  
  i=0
  while i < len(lines):
      line = lines[i]
      if(line.startswith("=== RUN")):
          if lines[i+1].startswith("--- FAIL:"):
              fails.append(i+1)
      i+=1
  
  if len(sys.argv) == 1:
      n = 0
      for i in fails:
          print(n, lines[i], end='')
          n += 1
      sys.exit(len(fails))
  
  n = int(sys.argv[1])
  k = fails[n]+2
  got = []
  want = []
  while not lines[k].startswith("want:"):
      #print(lines[k])
      got.append(lines[k])
      k += 1
  k += 1
  while not (lines[k].startswith("FAIL") or lines[k].startswith("=== RUN")):
      #print(lines[k])
      want.append(lines[k])
      k += 1
  
  import tempfile
  import os
  
  f1n = "%s.got"%base
  
  f2n = "%s.want"%base
  
  with open(f1n, "w") as f1:
      with open(f2n, "w") as f2:
          f1.writelines(got)
          f2.writelines(want)
  
  os.system("diff %s %s" % (f1n, f2n))
  
  