-- | Return the argument of a boolean negation expression
viewNotExp :: C.Exp -> Maybe C.Exp
viewNotExp (C.UnOp C.Lnot a _)                     = Just a
viewNotExp :: C.Exp -> Maybe C.Exp
viewNotExp (C.UnOp C.Lnot a _)                     = Just a
viewNotExp (C.UnOp C.Lnot a _)                     = Just a