PC Logo 里红绿灯怎么画

PC Logo 里红绿灯的编写语言如下：
to ex1
setpc 12
stampoval 50 50
pu rt 90 fd 150 lt 90 pd
setpc 14
stampoval 50 50
pu rt 90 fd 150 lt 90 pd
setpc 10
stampoval 50 50
pu home pd
end

to hld
ex1
setpc 12
fill
wait 300
pe (stampoval 48 48 "true)
pu rt 90 fd 150 lt 90 pd
setpc 14
fill
wait 100
pe (stampoval 48 48 "true)
pu rt 90 fd 150 lt 90 pd
setpc 10
fill
wait 300
pe (stampoval 48 48 "true)
pu lt 90 fd 150 rt 90 pd
setpc 14
fill
wait 100
pe (stampoval 48 48 "true)
pu home pd
hld
end
执行：hld

怎么画