Extra functions on Lean.SMap

def Lean.SMap.foldM {α : Type u_1} {σ : Type w} {β : Type u_2} {m : Type w → Type w} [Monad m] [BEq α] [Hashable α] (f : σ → α → β → m σ) (init : σ) (map : Lean.SMap α β) : m σ

Monadic fold over a staged map.