docs: def formatwarning(message, category, filename, lineno, line=None):
      """
      Override default Warning layout, from:
  
          /PATH/TO/dutree.py:326: UserWarning:
              [Errno 2] No such file or directory: '/0.d/05.d'
            warnings.warn(str(e))
  
      To:
  
          dutree.py:330: UserWarning:
              [Errno 2] No such file or directory: '/0.d/05.d'
      """
      return '{basename}:{lineno}: {category}: {message}\n'.format(
          basename=path.basename(filename), lineno=lineno,
          category=category.__name__, message=message)