anchor.diff:  """    
       =>  [ 2, 17, 5, 13
             3, 18, 5, 13
  -          4, 11, 5, 13 ]
  +          (4, 6, 5, 13) ]
   
   
   [<Test>]
  
positive.code:         ()
  """
      => [ 2, 0, 4, 10
           3, 8, 4, 10 ]
  
  [<Test>]
  let `` match guarded clause`` () =
  
negative.code:         ()
      ()
  """
  //    |> parseTree
      => [(2, 0, 9, 6)
          (2, 12, 5, 6)
          (3, 11, 4, 10)
          (7, 4, 9, 6)
          (7, 11, 8, 10)]
  
  [<Test>]
  let ``code quotation`` () =
  