9;i&#39;&quot;
// Prints &quot;3: &#39;f&#39;&quot;
// Prints &quot;4: &#39;t&#39;&quot;</code></pre>

<p>When enumerating a collection, the integer part of each pair is a counter
for the enumeration, not necessarily the index of the paired value.
These counters can only be used as indices in instances of zero-based,
integer-indexed collections, such as <code>Array</code> and <code>ContiguousArray</code>. For
other collections the counters may be out of range or of the wrong type
to use as an index. To iter