title: Hadoop Pig: Extract all substrings matching a given regular expression
body: <p>I am parsing some data of the form:</p>
  
  <pre><code>(['L123', 'L234', 'L1', 'L253764'])
  (['L23', 'L2'])
  (['L5'])
  ...
  </code></pre>
  
  <p>where the phrases inside the parens, including the brackets, are encoded as a single chararray.</p>
  
  <p>I want to extract just the L+(digits) tags to obtain tuples of the form:</p>
  
  <pre><code>((L123, L234, L1, L253764))
  ((L23, L2))
  ((L5))
  </code></pre>
  
  <p>I have tried using REGEX_EXTRACT_ALL using the regular expression '(L\d+)', but it only seems to extract a single tag per line, which is useless to me. Is there a way to create tuples in the way I have described above?</p>