fix: change noRollback to NoRollback

Author: tyru

dsl/op/array.go

@@ -22,5 +22,5 @@ func (*arrayOp) String() string {
 
 // Execute executes "$array" operation
 func (*arrayOp) Expand(args []types.Value) (types.Value, func(), error) {
-	return types.NewArray(args, types.AnyValue), noRollback, nil
+	return types.NewArray(args, types.AnyValue), NoRollback, nil
 }

dsl/op/expand_macro.go

@@ -25,7 +25,7 @@ func (*expandMacroOp) String() string {
 // Execute executes "$expand-macro" operation
 func (*expandMacroOp) Expand(args []types.Value) (types.Value, func(), error) {
 	if err := signature(types.AnyValue).check(args); err != nil {
-		return nil, noRollback, err
+		return nil, NoRollback, err
 	}
 	return args[0].Eval(context.Background())
 }

dsl/op/invert.go

@@ -23,8 +23,8 @@ func (*invertOp) String() string {
 // Execute executes "$invert" operation
 func (*invertOp) Expand(args []types.Value) (types.Value, func(), error) {
 	if err := signature(types.AnyValue).check(args); err != nil {
-		return nil, noRollback, err
+		return nil, NoRollback, err
 	}
 	val, err := args[0].Invert()
-	return val, noRollback, err
+	return val, NoRollback, err
 }

dsl/op/rollback.go

@@ -1,3 +1,5 @@
 package op
 
-var noRollback = func() {}
+// NoRollback is an empty function.
+// intepreter can skip this function.
+var NoRollback = func() {}