title: Replacing specific characters after a string match
body: <p>I'm looking to replace specific characters  in numbers I'm extracting but I cannot figure out how to do so. 
  Here "," is the float separator and (' or .) are thousands separators. I can match this way :</p>
  
  <pre><code>&gt;&gt;&gt; myString = "I buy 456'123,45 then 45.654 then 123. I'm 30."
  &gt;&gt;&gt; re.findall(r"(?:\d+)(?:['|.]\d+)+(?:[,]\d+)?", myString)
  ["456'123,45", '45.654']
  </code></pre>
  
  <p>I want to replace in my string all thousands separator to get this :</p>
  
  <pre><code>&gt;&gt;&gt; newString
  "I buy 456123,45 then 45654 then 123. I'm 30."
  </code></pre>
  
  <p>I'm pretty sure I need to use groups and subgroups in order to replace what I want but I don't know how to deal with groups when "()+" is present, the length of the number can also be very long
  (e.g : 123'456'789'123'456'789,123)</p>
  
  <p>Thanks</p>