code: def relpath(path, start=posixpath.curdir):
      
      if not path:
          raise ValueError("no path specified")
  
      start_list = posixpath.abspath(start).split(posixpath.sep)
      path_list = posixpath.abspath(path).split(posixpath.sep)
  
      # Work out how much of the filepath is shared by start and path.
      i = len(posixpath.commonprefix([start_list, path_list]))
  
      rel_list = [posixpath.pardir] * (len(start_list) - i) + path_list[i:]
      if not rel_list:
          return posixpath.curdir
      return posixpath.join(*rel_list)
docs: Return a relative version of a path