fact: Axiom uniq_remove_mid : uniq (E ++ F ++ G) -> uniq (E ++ G).
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.AssocList Metalib.MetatheoryAtom Metalib.LibTactics