∀ {α : Type u_1} {β : Type u_2} [inst : TopologicalSpace α] [inst_1 : Preorder α] [OrderClosedTopology α]
  [inst_3 : Preorder β] [IsDirectedOrder β] [Nonempty β] {f : β → α} {a : α},
  Antitone f → Filter.Tendsto f Filter.atTop (nhds a) → IsGLB (Set.range f) a