public FunctionScope(Scope parent, FunctionDeclaration function)
            : base(parent)
        {
            if (function == null)
                ThrowHelper.ThrowArgumentNullException(() => function);

            Function = function;
        }
 public static FunctionScope CreateFunctionScope(this Scope scope, FunctionDeclaration function)
 {
     if (function == null)
         ThrowHelper.ThrowArgumentNullException(() => function);
     return new FunctionScope(scope, function);
 }