Add "?" test

ts_example/test.ts

@@ -4,11 +4,10 @@ function add(a: number, b: int, c: string, d: bigint): number {
   return a + b;
 }
 
-export function floatArrayToNumberArray(a: Float32Array): number[] { 
+export function floatArrayToNumberArray(a: Float32Array): number[] {
   return Array.from(a);
 }
 
-
 function concat(a: string, b: string): string {
   return a + b;
 }
@@ -46,3 +45,13 @@ const concat3 = (a: string, b: string): string => {
 (a: string, b: string): string => {
   return a + b;
 };
+
+export function addMaybe(a: number | undefined, b?: number): number {
+  if (a === undefined) {
+    return 0;
+  }
+  if (b === undefined) {
+    return a;
+  }
+  return a + b;
+}