code: def append_exception(self,
                           stacktrace):
          
          # Delete the last message of the list
          if len(self.exceptions) > 0:
              del self.exceptions[-1]
  
          # Append the new message at the top
          self.exceptions.insert(0, stacktrace)
          self.changes_made = True
  
          # Redraw
          self.redraw()
docs: Appends the given exception at the top of the exception list and delete the oldest one (bottom most).
          :param stacktrace: Stacktrace string as returned by 'traceback.format_exc()' in an 'except' block.