%!PS-Adobe-2.0
% ----- Define box procedure ---
/box
{ 72 0 rlineto
  0 72 rlineto
  -72 0 rlineto
  closepath } def
% --------- Begin Program -----------
newpath % First box
  252 324 moveto box
  0 setgray fill
newpath % Second box
  270 360 moveto box
  .4 setgray fill
newpath % Third box
  288 396 moveto box
  .8 setgray fill
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