/scalefactor 1 def
/counter 0 def
/DecreaseScale {
scalefactor .2 sub
/scalefactor exch def
} def

/IncreaseCounter { /counter counter 1 add def } def

/trappath {
0 0 moveto 90 0 rlineto
-20 45 rlineto -50 0 rlineto
closepath
} def

/doATrap {
gsave
1 scalefactor scale
trappath
counter 2 mod
0 eq {.5} {0} ifelse
setgray fill
grestore
} def

250 350 translate

5 {IncreaseCounter doATrap DecreaseScale 0 20 translate} repeat

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