def sibLink(self, name):
        """
        Return the text that links to a sibling of the requested resource.

        @param name: The sibling resource
        @type name: C{bytes}

        @return: A relative URL.
        @rtype: C{bytes}
        """
        if self.postpath:
            return (len(self.postpath)*b"../") + name
        else:
            return name

        Return the text that links to a sibling of the requested resource.

        @param name: The sibling resource
        @type name: C{bytes}

        @return: A relative URL.
        @rtype: C{bytes}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/server.py