def chattr(self, path, attr):
return SFTP_OP_UNSUPPORTED<EOL>
Change the attributes of a file.  The ``attr`` object will contain
only those fields provided by the client in its request, so you
should check for the presence of fields before using them.

:param str path:
    requested path (relative or absolute) of the file to change.
:param attr:
    requested attributes to change on the file (an `.SFTPAttributes`
    object)
:return: an error code `int` like ``SFTP_OK``.