is_ptree : term -> bool
- is_ptree ``t:unit ptree``; val it = false: bool - is_ptree ``Branch 1 2 (Leaf 2 2) (Leaf 3 3)``; val it = false: bool - is_ptree ``Branch 0 0 (Leaf 1 1) (Leaf 2 2)``; val it = true: bool