<li>the index <code>x</code> is <i>in range</i> if <code>0 &lt;= x &lt; len(a)</code>,
	    otherwise it is <i>out of range</i></li>
</ul>

<p>
For <code>a</code> of <a href="#Array_types">array type</a> <code>A</code>:
</p>
<ul>
	<li>a <a href="#Constants">constant</a> index must be in range</li>
	<li>if <code>x</code> is out of range at run time,