anchor.diff:          Assert.AreEqual(1, max)
           Assert.AreEqual(0, min)
           Assert.AreEqual(0.5, average)
  +
  +
  +    [<Test>]
  +    member this.CalculateStatisticsTest_6 () =
  +        let (max, min, average) = tree_5.CalculateStatistics "e"
  +        Assert.AreEqual(2, max)
  +        Assert.AreEqual(1, min)
  +        Assert.AreEqual(1.5, average)
  +
  +    [<Test>]
  +    member this.CalculateStatisticsTest_7 () =
  +        let (max, min, average) = tree_5.CalculateStatistics "s"
  +        Assert.AreEqual(4, max)
  +        Assert.AreEqual(3, min)
  +        Assert.AreEqual(3.5, average)
   
       [<Test>]
       member this.GetTypeOfExpressionTest_4 () =
  
positive.code:     else*) System.IO.Directory.CreateDirectory directoryPath |> ignore
      let t = new CommonAstTest () 
  
      tree_4.AstToDot numToString tokenToNumber (Some tokenData) leftSide path
  
      t.FindNonterminalsByIndTest ()
      t.FindNonterminalsByStringTest ()
  
negative.code: 
  let tree_4 = new Tree<TokenType>(tokens_4, ast6_4, [||], Some leftSide, Some numToString)
  
  let tokens_5 = [|NUM 1; PLUS 2; NUM 3; PLUS 4; NUM 5; PLUS 6; NUM 7; MULT 8; NUM 9;|]
  
  let ast1_5 = getAst <| getFamily 2 (getNodes [|terminal0|]) <| null
  let ast1_2_5 = getAst <| getFamily 2 (getNodes [|terminal0|]) <| null
  let ast2_5 = getAst <| getFamily 4 (getNodes [|ast1_5; ast1_2_5; terminal1; terminal2|]) <| null
  let ast3_5 = getAst <| getFamily 0 (getNodes [|ast1_5; terminal1; terminal2|]) <| null
  let ast4_5 = getAst 
             <| getFamily 0 (getNodes [|ast2_5; terminal3; terminal4|]) 
             <| [| getFamily 0 (getNodes [|ast3_5; terminal5; terminal6|]) |]
  let ast5_5 = getAst <| getFamily 0 (getNodes [|terminal7; terminal8|]) <| null
  let ast6_5 = getAst <| getFamily 0 (getNodes [|ast4_5; ast5_5; terminal7; terminal8|]) <| null
  let ast7_5 = getAst <| getFamily 1 (getNodes [|ast6_5|]) <| null
  
  let tree_5 = new Tree<TokenType>(tokens_5, ast7_5, [||], Some leftSide, Some numToString)
  
  let tokenToNumber = function
      | NUM _ -> 4
      | PLUS _ -> 5
  