exact absurd rfl hneq
case cons.inr.head
κ : Type u_1
ν : Type u_2
inst✝ : DecidableEq κ
kv : κ × ν
kvs : List (κ × ν)
ih : kv.fst ∈ map Prod.fst (matchKey kvs kv.fst).snd → False
hneq : ¬kv.fst = kv.fst
⊢ kv.fst ∈ map Prod.fst (matchKey kvs kv.fst).snd
no goals