maps grow to accommodate the number of items
stored in them, with the exception of <code>nil</code> maps.
A <code>nil</code> map is equivalent to an empty map except that no elements
may be added.
</p>

<h3 id="Channel_types">Channel types</h3>

<p>
A channel provides a mechanism for
<a href="#Go_statements">concurrently executing functions</a>
to communicate by
<a href="#Send_statements">sending</a> and