How is this argument making its way to a called function?
<p>code:</p>

<pre><code>function onDeviceReady() {
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail);
}

function gotFS(fileSystem) {
    fileSystem.root.getFile("readme.txt", {create: true, exclusive: false}, gotFileEntry, fail);
}
</code></pre>

<p>What I don't understand is how does fileSystem get passed when there are no arguments passed with gotFS in the requestFileSystem?</p>
