<pre class="shiki github-dark shaku"><code>/*type Callback = (error: Error, data: any) =&gt; voidtype AsyncFunc = ( callback: Callback, data: any) =&gt; void*//** * @param {AsyncFunc[]} funcs * @return {(callback: Callback) =&gt; void} */function sequence ( funcs ) { return function callRec ( cb, input, len=0 ) { funcs[len](( error, resp ) =&gt; { if ( error ) cb(error, undefined); else if ( len === funcs.length - 1 ) cb(undefined, resp); else { callRec(cb, resp, len + 1); } }, input); }}</code></pre>

Easy recursive solution, without promise !!

This problem is similar to 11. what is Composition? create a pipe(). You are asked to implement an async function helper, sequence() which chains up a…