code: def reverse(path):
      
      if is_rooted(path) or '..' in path:
          from b2.manager import get_manager
          get_manager().errors()(
              'reverse(path): path is either rooted or contains ".." in the path')
      if path == '.':
          return path
      path = os.path.normpath(path)
      # os.sep.join() is being used over os.path.join() due
      # to an extra '..' that is created by os.path.join()
      return os.sep.join('..' for t in path.split(os.sep))
docs: Returns path2 such that `os.path.join(path, path2) == '.'`.
      `path` may not contain '..' or be rooted.
  
      Args:
          path (str): the path to reverse
  
      Returns:
          the string of the reversed path
  
      Example:
  
          >>> p1 = 'path/to/somewhere'
          >>> p2 = reverse('path/to/somewhere')
          >>> p2
          '../../..'
          >>> os.path.normpath(os.path.join(p1, p2))
          '.'