请添加在问题和答案中折叠代码块的功能

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 alert('Most folded code ever!'); 

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<details>
  <summary>Some details</summary>
  <p>More info about the details.</p>
</details>

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// ==UserScript==
// @name           Code folding
// @namespace      http://stackoverflow.com/
// @include        http://stackoverflow.com/questions/*
// @include        http://meta.stackexchange.com/questions/*
// ==/UserScript==

//default values

// Add a selector for each element that you wish to fold
// to the array below (one array item per selector
var elementsToFold = new Array("pre:has(code)");

// Close elements by default?
var closeByDefault = true;

//-------------------------------
//- Do not edit below this line -
//-------------------------------
function getJQuery() {
    if (typeof unsafeWindow.jQuery == 'undefined') {
        window.setTimeOut( getJQuery, 100 );
    }
    else {
        $ = unsafeWindow.jQuery; letsGo();
    }
}
//add the folded style into the document
var style = window.document.createElement("style");
style.type = "text/css";
style.innerHTML = ".folded {height:1.0em; overflow:hidden;cursor:N-resize;}";
document.getElementsByTagName("HEAD")[0].appendChild(style);

getJQuery();

function letsGo () {
    $(elementsToFold.join(",")).click( function() {
            $(this).toggleClass("folded");
            });
    window.showHideElements = function (event) {
        alert(event.innerHTML);
    }
    window.hideAllElements = function () {
        $(elementsToFold.join(",")).each(function() {
                $(this).addClass("folded");
                });
    }
    window.showAllElements = function () {
        $(elementsToFold.join(",")).each(function() {
                $(this).removeClass("folded");
                });
    }

    if (closeByDefault) {
        $(elementsToFold.join(",")).each(function() {
                $(this).addClass("folded");
                });
    }

    GM_registerMenuCommand("Show all folded blocks", showAllElements);
    GM_registerMenuCommand("Hide all foldable blocks", hideAllElements);
}

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