title: How to get the list of error numbers (Errno) for an Exception type in python?
body: <p>For a specific Exception type (let's say for IOError), how can i extract the complete list of Errnos and descriptions like this:</p>
  
  <p>Errno 2: No such file or directory</p>
  
  <p>Errno 122: Disk quota exceeded</p>
  
  <p>...</p>