pr -l 63 Digraph.scala            >Digraph.pr
pr -l 63 DigraphList.scala        >DigraphList.pr
pr -l 63 Test_DigraphList.scala   >Test_DigraphList.pr
pr -l 63 DigraphMap.scala         >DigraphMap.pr
pr -l 63 Test_DigraphMap.scala    >Test_DigraphMap.pr
chmod 644 *.scala *.pr