proposition: Lemma fcat_nil' s : fcat' nil (seq_of s) = s.
proof: Proof. elim/fmap_ind': s=>[|k v s L IH] //=. by rewrite seqof_ins //= (_ : FinMap _ = ins k v nil) // fcat_ins' ?notin_path // IH. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path) pcm(options)