anchor.diff:      function GenerateUserFuncBody(const FuncBody: Compute.ExprTrees.Expr): string;
     protected
       procedure Visit(const Node: IVariableNode); override;
  +    procedure Visit(const Node: ILambdaParamNode); override;
     public
       constructor Create;
     end;
  
positive.code: begin
    inherited Create;
  
    FFunctions := TDictionaryImpl<string, Expr.NaryFunc>.Create;
  end;
  
  destructor TExprFunctionCollector.Destroy;
  
negative.code:   result := Output;
  end;
  
  procedure TUserFuncBodyGenerator.Visit(const Node: ILambdaParamNode);
  begin
    Emit('arg' + Node.Data.Name);
  end;
  
  procedure TUserFuncBodyGenerator.Visit(const Node: IVariableNode);
  begin
    raise ENotImplemented.Create('Variables in functions not implemented');
  