axiom コマンドと CoeFun の使用例：(SKI コンビネータ計算)

inductive Lam : Type where
  | S : Lam
  | K : Lam
  | app : Lam → Lam → Lam

instance : CoeFun Lam (fun _ => Lam → Lam) where
  coe lambda := Lam.app lambda

namespace Lam

axiom K_def {a b : Lam} : K a b = a
axiom S_def {a b c : Lam} : S a b c = (a c) (b c)

theorem eta_simp {a b : Lam} : (∀(c : Lam), a c = b c) → a = b := by
  intro h
  specialize h S
  injection h

def I := S K K

theorem I_def {a : Lam} : I a = a := by rw [I, S_def, K_def]

example {a : Lam} : S K a = I := by
  apply eta_simp
  intro c
  rw [I_def, S_def, K_def]

end Lam

Start with the Lean example in the issue, especially the Lam type, CoeFun instance, axioms, and SKI combinator theorems. The intended documentation location and requested change are not specified, so first clarify where this example belongs and what form the completed example should take before editing or testing it.