     <p>Returns the least significant <code>width</code> bits of this big integer as a
non-negative number (i.e. unsigned representation).  The returned value has
zeros in all bit positions higher than <code>width</code>.</p>
<pre class="language-dart"><code>new BigInt.from(-1).toUnsigned(5) == 31   // 11111111  -&gt;  00011111
</code></pre>
<p>This operation can be used to simulate arithmetic from low level languages.
For example, to increment an 8 bit quantity:</p>
<pre class="language-dart"><code>q = (q 