{HEAD ~ Method} for retrieving {TAIL ~ previous input commands} to an external program from an editor environment 
for retrieving
{ HEAD ~ Method } for retrieving { TAIL ~ previous input commands } to an external program from an editor environment
HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH