title: how to remove whitespace inside bracket?
body: <p>I have the following string:</p>
  
  <pre><code>res = '(321, 3)-(m-5, 5) -(31,1)'
  </code></pre>
  
  <p>I wanna remove the whitespace withing the bracket but i haven't any knowledge about regular expression</p>
  
  <p>I ve try this but that doesn't work:</p>
  
  <pre><code>import re
  res = re.sub(r'\(.*\s+\)', '', res)
  </code></pre>