Update iterable.md

docs/uts/buildin-object-api/iterable.md

@@ -244,7 +244,7 @@ class TestClass implements UTSValueIterable<any | null> {
 			return obj
 		}
 		
-}
+	}
 ```
 执行结果:
 
@@ -268,28 +268,30 @@ item null
 
 
 ```typescript
-class TestClass implements UTSValueIterable<any> {
+	class TestClass implements UTSValueIterable<any | null> {
 		
 		holderArray: (any | null)[] = [11, 22, null, 33, 44, null]
     
-	valueIterator(): UTSIterator<any> {
+		valueIterator(): UTSIterator<any | null> {
 			let holderIndex = 0;
       let arr = this.holderArray.filter((value) => { 
         return value != null
       })
       
-		let obj: UTSIterator<any> = {
-			next: () : UTSIteratorResult<any> => {
+			let obj: UTSIterator<any | null> = {
+        
+				next: () : UTSIteratorResult<any | null> => {
           const done = holderIndex == arr.length
           return {
             done,
             value: done ? null : arr[holderIndex++],
-				} as UTSIteratorResult<any>
+          } as UTSIteratorResult<any | null>
 				}
 			}
 			return obj
 		}
-}
+		
+	}
 
 ```