Why does jquery need _$ in case of overwrite?
<pre><code>var 
// Will speed up references to window, and allows munging its name.
window = this,
// Will speed up references to undefined, and allows munging its name.
undefined,
// Map over jQuery in case of overwrite
_jQuery = window.jQuery,
// Map over the $ in case of overwrite
_$ = window.$,

jQuery = window.jQuery = window.$ = function( selector, context ) {
    // The jQuery object is actually just the init constructor 'enhanced'
    return new jQuery.fn.init( selector, context );
};
</code></pre>

<p>Why does jQuery need "_$ = window.$" or "_jQuery = window.jQuery"? It doesn't make sense to me, but without this two lines, the framework doesn't work.</p>

<p>Thanks for any help..</p>
