exact lookupTypeFromCHeadersUnique cs ⟨s_nm, hn⟩
η : Type u_η
dec_η : DecidableEq η
schema : Schema
nm : η
τ : Type u_1
hs : List Header
fst✝ : Header
pf : HasCol fst✝ ((nm, τ) :: hs)
cs : List (CertifiedHeader ((nm, τ) :: hs))
s_nm : η
hn : HasName s_nm (map Sigma.fst cs)
⊢ lookupType ((nm, τ) :: hs) { fst := s_nm, snd := hasNameOfFromCHeaders hn } =
    lookupType (map Sigma.fst cs) { fst := s_nm, snd := hn }
no goals