e>meta</code> (refered to as &ldquo;the meta tree&rdquo;) must meet:</p>

<ul>
<li>Any metas that should be seen as nil values by the decoder (for which <code>decodeNil</code> on e.g. <code>KeyedDecodingContainer</code> should return true) must conform to <code><a href="../Protocols.html#/s:17MetaSerialization03NilA0P">NilMeta</a></code>.</li>
<li><p>If you didn&rsquo;t set the <code>MetaDecoder.Options.dynamicallyUnwindMetaTree</code> option on this decoder, all metas that can be seen as keyed or unkeyed c