When the coil is removed from an endoscope, the practitioner or the assistant observes the coil as it is withdrawn and notices the appearance of the stripes as an indication that {HEAD ~ the distal end} of {TAIL ~ the instrument} is not far away 
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When the coil is removed from an endoscope , the practitioner or the assistant observes the coil as it is withdrawn and notices the appearance of the stripes as an indication that { HEAD ~ the distal end } of { TAIL ~ the instrument } is not far away
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH