The notches hence cooperate with {HEAD ~ the pins} to serve {TAIL ~ the above discussed functions} of the pins 
to serve
The notches hence cooperate with { HEAD ~ the pins } to serve { TAIL ~ the above discussed functions } of the pins
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH