<pre class="shiki github-dark shaku"><code>type MyNonNullable&lt;T&gt; = T extends null | undefined ? never : T;// your code here, don't use NonNullable&lt;T&gt; in your code</code></pre>

This is my accepted solution

NonNullable<T> returns a type by excluding null and undefined from T. Please implement MyNonNullable<T> by yourself. type Foo = 'a' | 'b' | null | und…