and <code>B2</code> is <code>string</code>.
The underlying type of <code>[]B1</code>, <code>B3</code>, and <code>B4</code> is <code>[]B1</code>.
</p>

<h3 id="Method_sets">Method sets</h3>
<p>
A type has a (possibly empty) <i>method set</i> associated with it.
The method set of an <a href="#Interface_types">interface type</a> is its interface.