sequence of chunks for FileOut param #0
sequence of chunks for FileOut param #1 etc.
+=head3 INITIAL MESSAGE
+
+Because the underlying channel (QEmu -net channel) doesn't have any
+sort of connection control, when the daemon launches it sends an
+initial word (C<GUESTFS_LAUNCH_FLAG>) which indicates that the guest
+and daemon is alive. This is what C<guestfs_wait_ready> waits for.
+
=head1 ENVIRONMENT VARIABLES
=over 4