{"ast_node_type":"other","tokens":[{"end":34,"kind":"keyword","start":0,"text":"//"}]}
        // Remove double negation.
        CfgExpr::Atom(atom) => CfgExpr::Not(Box::new(CfgExpr::Atom(atom.clone()))),
        CfgExpr::Not(expr) => make_nnf(expr),