title: Replace strings in a list (using re.sub)
body: <p>I am trying to replace parts of file extensions in a list of files. I would like to be able to loop through items (files), and remove the extensions. I don't know how to appropriately loop through items in the list when re.sub as the third parameter requires a string.  eg. re.sub(pattern, repl, string, count=0, flags=0) </p>
  
  <pre><code>import re
  
  file_lst = ['cats1.fa', 'cats2.fa', 'dog1.fa', 'dog2.fa']
  file_lst_trimmed =[]
  
  for file in file_lst:
      file_lst_trimmed = re.sub(r'1.fa', '', file)
  </code></pre>
  
  <p>The issue arising here is that re.sub expects a string and I want it to loop through a list of strings. </p>
  
  <p>Thanks for any advice!</p>