title: extract characters between parenthesis with conditions
body: <pre><code>a = '{a=[],b=[],c=[ab=cd,ef=gh],d=[ij=kl],e=[]}'
  </code></pre>
  
  <p>How can I extract characters between parenthesis <strong>[ ]</strong> from above string that are after <strong>=</strong>. 
  Output expected is:</p>
  
  <pre><code>'cd','gh','kl'
  </code></pre>