old_contents: v1=0
  
  def f1():
      if v1:
          v2 = 2 + 3 * 4 / 7 << 3;
          return v2
      elif v2:
          a, b = 1, 2
          b, a = a, b
          return 0
      else:
          print 7
          return 1
      return 0                            # unreachable
  
  def f2():
      if v1:
          return 0
      return 0
  
  def f3():
      if v1:
          raise v1
      else:
          raise v1
      print v1                            # unreachable
  
  def f4():
      assert None
      print v1                            # unreachable
  
  def f5():
      assert 1
      print v1
      
  def f6():
      assert 0
      print v1                            # unreachable
  
  
  def f7():
      global v1
      try:
          assert None
      except KeyError:
          v1 = 7
      else:
          raise v1
      return 0
  
  def f8():
      try:
          print v1()
      except KeyError:
          return 7
      else:
          raise v1
      return 0                            # unreachable
  
new_contents: v1=0
  
  def f1():
      if v1:
          v2 = 2 + 3 * 4 / 7 << 3;
          return v2
      elif v2:
          a, b = 1, 2
          b, a = a, b
          return 0
      else:
          print 7
          return 1
      return 0                            # unreachable
  
  def f2():
      if v1:
          return 0
      return 0
  
  def f3():
      if v1:
          raise v1
      else:
          raise v1
      print v1                            # unreachable
  
  def f4():
      assert None
      print v1                            # unreachable
  
  def f5():
      assert 1
      print v1
      
  def f6():
      assert 0
      print v1                            # unreachable
  
  
  def f7():
      global v1
      try:
          assert None
      except KeyError:
          v1 = 7
      else:
          raise v1                        # unreachable
      return 0
  
  def f8():
      try:
          print v1()
      except KeyError:
          return 7
      else:
          raise v1
      return 0                            # unreachable
  
subject: update comment to reflect what checker does