Optional additional steps of repeating {TAIL ~ the procedure} or {HEAD ~ washing steps} can also be included 
Optional additional steps of repeating { TAIL ~ the procedure } or { HEAD ~ washing steps } can also be included
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH