)</p>

<p>Arrays use Copy-on-Write so that their storage and elements are
only copied lazily, upon mutation, when more than one array
instance is using the same buffer.  Therefore, the first in any
sequence of mutating operations may cost <code>O(N)</code> time and space,
where <code>N</code> is the length of the array.</p>

<h2>Growth and Capacity</h2>

<p>When an array&#39;s contiguous storage fills up, new storage must be
allocated and elements must be moved to the new storage.  <code>Array</code>,
<code