fact: Definition extract_unit (st:state) := match unit_stack st with | nil => None | e::us => Some(e , set_unit_stack us st) end.
imports: Cdcl.PatriciaR Cdcl.KeyInt Cdcl.ReifClasses Cdcl.Lib Bool Setoid ZifyBool ZArith Uint63 Lia List Cdcl.Syntax Cdcl.Clause