 = [&quot;1&quot;, &quot;2&quot;, &quot;three&quot;, &quot;///4///&quot;, &quot;5&quot;]

let mapped: [Int?] = numbers.map { str in Int(str) }
// [1, 2, nil, nil, 5]

let flatMapped: [Int] = numbers.flatMap { str in Int(str) }
// [1, 2, 5]</code></pre>

<p><strong><code>transform</code>:</strong>  A closure that accepts an element of this
  sequence as its argument and returns an optional value.
<strong>Returns:</strong> An array of the non-<code>nil</code> results of calling <code>transform</code>
  with e