<a href="#Interface_types">interface type</a>, but not a
<a href="#Type_parameter_declarations">type parameter</a>, and each non-interface type
<code>T</code> listed in a case must implement the type of <code>x</code>.
The types listed in the cases of a type switch must all be
<a href="#Type_identity">different</a>.
</p>

<pre class="ebnf">

   * Where there's a hierarchy in the types, list it via a parent
   * Highly specific magic matches get a high priority
   * General magic matches which could trigger a false-positive need
     a low one
   * The priority for containers normally need to be higher than for
     the things they contain, so they don't accidently get detected
     as what's in them
   * For logic too complex to be expressed in a magic match, do the best