w()
			<-limit
		}(w)
	}
	select{}
}
</pre>

<h3 id="locks">Locks</h3>

<p>
The <code>sync</code> package implements two lock data types,
<code>sync.Mutex</code> and <code>sync.RWMutex</code>.
</p>

<p class="rule">
For any <code>sync.Mutex</code> or <code>sync.RWMutex</code> variable <code>l</code> and <i>n</i> &lt; <i>m</i>,