feat(append): add append function

Author: djcsdy

index.test.ts

@@ -3,6 +3,7 @@ import {
     all,
     and,
     any,
+    append,
     asyncIterable,
     average,
     concat,
@@ -327,3 +328,15 @@ test("prepend", async t => {
     );
     t.deepEqual(await toArray(prepend(asyncIterable([1, 2, 3]))(asyncIterable([]))), [1, 2, 3]);
 });
+
+test("append", async t => {
+    t.deepEqual(
+        await toArray(append(asyncIterable([4, 5, 6]))(asyncIterable([1, 2, 3]))),
+        [1, 2, 3, 4, 5, 6]
+    );
+    t.deepEqual(
+        await toArray(append(asyncIterable<number>([]))(asyncIterable([1, 2, 3]))),
+        [1, 2, 3]
+    );
+    t.deepEqual(await toArray(append(asyncIterable([4, 5, 6]))(asyncIterable([]))), [4, 5, 6]);
+});

index.ts

@@ -898,3 +898,9 @@ export function prepend<T>(a: AsyncIterableLike<T>): (b: AsyncIterableLike<T>) =
 }
 
 export const asyncPrepend = prepend;
+
+export function append<T>(b: AsyncIterableLike<T>): (a: AsyncIterableLike<T>) => AsyncIterable<T> {
+    return a => concat([a, b]);
+}
+
+export const asyncAppend = append;