title: Create a list containing files of each transaction
body: <p>Good evening, I want to create a list while reading a text file (historique.txt) which contains list of files associated to each taskid. Considering the following example: my text file contains these lines:</p>
  
  <pre><code>4,file1
  4,file2
  5,file1
  5,file3
  5,file4
  6,file3
  6,file4
  </code></pre>
  
  <p>(to explain more the content of the text file: 4 is an idtask and file1 is a file used by idtask=4, so basically, task 4 used (file1,file2).
  I want to obtain list Transactions=<code>[[file1,file2],[file1,file3,file4],[file3,file4]]</code>
  Any help and thank you.</p>