anchor.diff:          | :? Epsilon as e -> Unchecked.defaultof<_>, true
           | _ -> failwith "Strange tree - consists of terminal"
       let order =
  -        let stack = new System.Collections.Generic.Stack<_>()
  +        let stack = new Stack<_>()
           match root with
           | :? AST as ast -> stack.Push ast
           | _ -> ()
  
positive.code:                     let res = filter ast.first
                      if res then forestFam := ast.first :: !forestFam
                      res
                  | _ -> failwith "Error in GetForestWithToken function"
  
              let mutable tree = fst <| this.GetNextTree [token] filter
  
  
negative.code:         newTree, finalUnprocessed
  
      ///<summary>
      /// Returns all trees that contain some token.
      /// <para> tokenName - name of token </para>
      /// <para> tokRange - range of token </para>
      ///</summary>
  