def posix_rename(self, oldpath, newpath):
return SFTP_OP_UNSUPPORTED<EOL>
Rename (or move) a file, following posix conventions. If newpath
already exists, it will be overwritten.

:param str oldpath:
    the requested path (relative or absolute) of the existing file.
:param str newpath: the requested new path of the file.
:return: an SFTP error code `int` like ``SFTP_OK``.

:versionadded: 2.2