best effort attempt to run C<$h-E<gt>sync> when the handle is closed
(also if the program exits without closing handles).
+=item $h->set_busy ();
+
+This sets the state to C<BUSY>. This is only used when implementing
+actions using the low-level API.
+
+For more information on states, see L<guestfs(3)>.
+
=item $h->set_path ($path);
Set the path that libguestfs searches for kernel and initrd.img.
Setting C<path> to C<NULL> restores the default path.
+=item $h->set_ready ();
+
+This sets the state to C<READY>. This is only used when implementing
+actions using the low-level API.
+
+For more information on states, see L<guestfs(3)>.
+
=item $h->set_verbose ($verbose);
If C<verbose> is true, this turns on verbose messages (to C<stderr>).