<<< native [ ESub (EIdentifier "P") (ENumber "0") , ESymbol Rel "=" , EUnderover False (ESub (EIdentifier "P") (ENumber "0")) (EPhantom (EIdentifier "x")) (EPhantom (EIdentifier "x")) ] >>> eqn P sub 0 = {P sub 0} from {hphantom x} to {hphantom x}