feat(asyncTailOnce): add asyncTailOnce function

Author: djcsdy

index.test.ts

@@ -1,6 +1,6 @@
 import type {ExecutionContext} from "ava";
 import test from "ava";
-import {asyncIterator} from "./index";
+import {asyncIterator, asyncTailOnce, asyncToArrayOnce} from "./index";
 
 test("asyncIterator(empty)", async t => {
     t.true((await asyncIterator([]).next()).done);
@@ -87,3 +87,9 @@ test("asyncIterator(Promise<Iterable<T>>", async t => {
 test("asyncIterator(Promise<Iterable<Promise<T>>>)", async t => {
     await verify123(t, asyncIterator(Promise.resolve(promiseGenerator123())));
 });
+
+test("asyncTailOnce", async t => {
+    t.deepEqual(await asyncToArrayOnce(asyncTailOnce(asyncIterator([1, 2, 3, 4]))), [2, 3, 4]);
+    t.deepEqual(await asyncToArrayOnce(asyncTailOnce(asyncIterator([1]))), []);
+    t.deepEqual(await asyncToArrayOnce(asyncTailOnce(asyncIterator([]))), []);
+});

index.ts

@@ -96,3 +96,9 @@ export async function asyncFirstOnce<T>(iterator: AsyncIteratorLike<T>): Promise
         return element.value;
     }
 }
+
+export function asyncTailOnce<T>(iterator: AsyncIteratorLike<T>): AsyncIterator<T> {
+    const it = asyncIterator(iterator);
+    const tail = it.next().then(() => it);
+    return fromPromiseOfIteratorLike(tail);
+}