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<html><title>W3.JS</title><script src="https://www.w3schools.com/lib/w3.js"></script><body><button onclick="w3.hide('p')">Hide all p elements</button><h2>London</h2><p>London is the capital city of England.</p><p>It is the most populous city in the United Kingdom.</p><p>Population over 13 million inhabitants.</p></body></html>