<<< native
[ ESubsup
    (EIdentifier "X")
    (ESubsup (EIdentifier "Z") (ENumber "4") (ENumber "3"))
    (ESubsup (EIdentifier "Y") (ENumber "2") (ENumber "1"))
, ESymbol Rel "="
, ESubsup
    (EIdentifier "X")
    (ESubsup (EIdentifier "Z") (ENumber "4") (ENumber "3"))
    (ESubsup (EIdentifier "Y") (ENumber "2") (ENumber "1"))
]
>>> eqn
X sub {Z sub 4 sup 3} sup {Y sub 2 sup 1} = X sub {Z sub 4 sup 3} sup {Y sub 2 sup 1}