to poly1 :x :y :z fd :x lt :y poly1 :x+:z :y :z end
to poly :x :y :z cs pd poly1 :x :y :z
to demo 
   print ['    Type in: ']
   print ['         poly 3 145 3   ']
   print ['to get the poly function. ']
   print ['    Change the numbers and see what you get (especially']
   print ['the middle one!)']  
end