50 setheight
20 setxunit
-2 2 setyrange
-4.5 9 setxrange

/I {2 0} def
/r 5 def

/I1 {I r 0 addv} def
/I2 {I r 0 subv} def

/hstep 3 def
/hangle 70 def
/fillstyle {hachure} def
I r 2 mul .4 () cframe*

xticks
xsubticks
xmarks
0 xtick
0 xmark
.7 setlinewidth
traceOx

I times2
I I1 15 Arc
I I2 15 Arc