teem	/	unrrdu	unu flip

unu flip: Reverse order of samples along one axis. Special case of
"unu shuffle".

Usage: unu flip -a <axis> [-i <nin>] [-o <nout>]

-a <axis> = axis to flip along (int)
 -i <nin> = input nrrd
-o <nout> = output nrrd (string); default: "-"