def sibling(name):
        """
        A file path for the directory containing the file at this file path.

        @param name: the name of a sibling of this path.  C{name} must be a
            direct sibling of this path and may not contain a path separator.

        @return: a sibling file path of this one.
        """

        A file path for the directory containing the file at this file path.

        @param name: the name of a sibling of this path.  C{name} must be a
            direct sibling of this path and may not contain a path separator.

        @return: a sibling file path of this one.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/filepath.py