title: Regex to match md5 hashes
body: <p>What type of regex should be used to match a md5 hash. </p>
  
  <p>how to validate this type of string <code>00236a2ae558018ed13b5222ef1bd987</code></p>
  
  <p>i tried something like this:  <code>('/^[a-z0-9]/')</code> but it didnt work.</p>
  
  <p>how to achieve this? thanks</p>