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