%!

72 dup scale
1 72 div setlinewidth
1 1 translate

/s 0.5 def

% g s = arguments to this procedure
% g entered first, s second
/fill-square { % the color shade g and the side s now sit on the stack
1 dict begin
% define s (local) to be the top value on the stack
/s exch def
% define g (local) to be the value now on the top of the stack
/g exch def
newpath
0 0 moveto
s 0 lineto
s s lineto
0 s lineto
closepath
gsave
g 0 0 setrgbcolor
fill
grestore
stroke
end } def

/g 1 def


gsave

10 {

g 1 fill-square

newpath
0 0 0.25 0 360 arc
gsave
g 0 0 setrgbcolor
fill
grestore
stroke

0.25 0.25 translate
/g g 0.1 sub def
} repeat

grestore


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