<<< native [ ESubsup (EIdentifier "L") (EIdentifier "x") (ENumber "2") , ESymbol Rel "=" , ESubsup (EIdentifier "L") (ESub (EIdentifier "x") (EPhantom (EIdentifier "z"))) (ESuper (ENumber "2") (EPhantom (EIdentifier "z"))) ] >>> mml $$L_x^2=L_{x_{\phantom{z}}}^{2^{\phantom{z}}}$$