[STATEMENT]
lemma [simp]: "\<eta>1 \<approx>>\<bullet> \<eta>2 \<Longrightarrow> NatTrans \<eta>1"
[PROOF STATE]
proof (prove)
goal (1 subgoal):
 1. \<eta>1 \<approx>>\<bullet> \<eta>2 \<Longrightarrow> NatTrans \<eta>1
[PROOF STEP]
by auto