A locked state managed by {HEAD ~ the blocker} greatly reduces corner cases and simplifies solutions in {TAIL ~ the few remaining corner cases} 
A locked state managed by { HEAD ~ the blocker } greatly reduces corner cases and simplifies solutions in { TAIL ~ the few remaining corner cases }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL