ne given
        .assert.callback(&apos;data&apos;, data =&gt; someChecksumFunction(data) === index.checksum, &apos;checksum&apos;)

        // only return the buffer
        .map.push(&apos;data&apos;);
});</code>
</code></pre>
<p>Note that the position-function works in a slightly restricted way, in that it only allows skipping forward without any additional configuration. @TODO See <code>Corrode#isSeeking</code> for more info.</p>
<p>In the way there&apos;s a <code>map.callback</code> there&apos;s also a