{TAIL ~ a receiving portion} which has a space for pulling in the second end portion of {HEAD ~ the stopper} 
{ TAIL ~ a receiving portion } which has a space for pulling in the second end portion of { HEAD ~ the stopper }
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD