initgraphics
clippath pathbbox pop exch pop 2 copy exch sub /range exch def
/step range 50.0 div def
0 200 translate
newpath
step exch {
	dup range div setgray
	0 0 moveto step 0 lineto step 100 lineto 0 100 lineto closepath
	fill
	step 0 translate
} for
