title: Regular expression in regards to question mark "lazy" mode
body: <p>I understand the <code>?</code> mark here means "lazy".</p>
  
  <p>My question essentially is <code>[0-9]{2}?</code> vs <code>[0-9]{2}</code></p>
  
  <p>Are they same?<br>
  If so, why are we writing the former expression? Aren't lazy mode more expensive performance wise?<br>
  If not, can you tell the difference?</p>