def _stat_owner(self, fp):
        """
        Get the filepath's owner's username.  If this is not implemented
        (say in Windows) return the string "0" since stat-ing a file in
        Windows seems to return C{st_uid=0}.

        (Reference:
        U{http://stackoverflow.com/questions/5275731/os-stat-on-windows})

        @param fp: L{twisted.python.filepath.FilePath}
        @return: C{str} representing the owner's username
        """
        try:
            userID = fp.getUserID()
        except NotImplementedError:
            return "0"
        else:
            if pwd is not None:
                try:
                    return pwd.getpwuid(userID)[0]
                except KeyError:
                    pass
            return str(userID)

        Get the filepath's owner's username.  If this is not implemented
        (say in Windows) return the string "0" since stat-ing a file in
        Windows seems to return C{st_uid=0}.

        (Reference:
        U{http://stackoverflow.com/questions/5275731/os-stat-on-windows})

        @param fp: L{twisted.python.filepath.FilePath}
        @return: C{str} representing the owner's username
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/ftp.py