all types in that type set must be maps, and they must all have identical key types.
</p>

<p>
If the map <code>m</code> is <code>nil</code> or the element <code>m[k]</code>
does not exist, <code>delete</code> is a no-op.
</p>


<h3 id="Length_and_capacity">Length and capacity</h3>

<p>
The built-in functions <code>len</code> and <code>cap</code> take arguments