def obs_nat
import bend-collections@1.0.0.0/src/containers/binary_heap.bend as BinaryHeapimport Base
import bend-collections@1.0.0.0/src/containers/types/binary_heap.bend as E
379def obs_nat(~A: Data, r: Heap<A> & Nat) -> Heap<A> & E.Obs<A>:
380 (h, n) = r
381 (h, E.ONat{n})