fact: Axiom binds_dec : (forall a b : A, {a = b} + {a <> b}) -> {binds x a E} + {~ binds x a E}.
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.AssocList Metalib.MetatheoryAtom Metalib.LibTactics