<<< native [ ESuper (EIdentifier "a") (ESymbol Bin "+") , ESymbol Rel "=" , EUnderover False (ESuper (EIdentifier "a") (ESymbol Bin "+")) (EPhantom (EIdentifier "x")) (EPhantom (EIdentifier "x")) ] >>> eqn a sup + = {a sup +} from {hphantom x} to {hphantom x}