fact: Fixpoint look_up (l: list (A * A)) (key: A): option A := match l with | nil => None | (k, v) :: l' => if equiv_dec k key then Some v else look_up l' key end.
imports: Coq.Lists.List Coq.micromega.Lia Coq.Sorting.Permutation Coq.ZArith.ZArith_base Coq.ZArith.Zcomplements Coq.Logic.FunctionalExtensionality CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext VST.zlist.sublist VST.zlist.list_solver