tree =

1^:<
   2^: <4^: <7^: <>, 0>, 5^: <>>,
   3^: <6^: <8^: <>, 9^: <>>, 0>>

pre  = ~&dvLPCo
post = ~&vLPdNCTo
in   = ~&vvhPdvtL2CTiQo
lev  = ~&iNCaadSPfavSLiF3RTaq

#cast %nLL

main = <.pre,in,post,lev> tree