title: Regex to exclude first and last characters of match
body: <p>I've the following string:
  word_word2_word3_word4</p>
  
  <p>My intention is to extract only 'test2'. Using <code>_\w*?_</code> as string match, I can get '<em>word2</em>' as match, but I can't see a way of removing those underscores to match only 'word2'.</p>
  
  <p>I can't use .split() or something like it, this value must be gathered using Regex only.</p>
  
  <p>What modifications do you suggest guys?</p>