The method involves passing {TAIL ~ editor input} to {HEAD ~ the external program}, wherein the external program evaluates the input, produces corresponding output, and transmits the output back to the editor 
The method involves passing { TAIL ~ editor input } to { HEAD ~ the external program } , wherein the external program evaluates the input , produces corresponding output , and transmits the output back to the editor
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH