running {HEAD ~ a shortest path algorithm} with {TAIL ~ the current location} and the destination location or the destination region 
with
running { HEAD ~ a shortest path algorithm } with { TAIL ~ the current location } and the destination location or the destination region
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH