// command to print OFF file
aaj::=foreach vertex do { printf "%f %f %f \n",x,y,z }
bbj::=foreach facet ff do { printf "3 ";\
       foreach ff.vertex do printf "%g ",id-1; printf "\n"}
do_off::= {printf "OFF\n%g %g %g\n",vertex_count,facet_count,edge_count;aaj;bbj}

