<<< native
[ EUnder
    True
    (EMathOperator "lim")
    (EGrouped
       [ EIdentifier "z"
       , ESymbol Rel "\8594"
       , ESub (EIdentifier "z") (ENumber "0")
       ])
, EIdentifier "f"
, EDelimited "(" ")" [ Right (EIdentifier "z") ]
, ESymbol Rel "="
, EIdentifier "f"
, EDelimited
    "(" ")" [ Right (ESub (EIdentifier "z") (ENumber "0")) ]
]
>>> eqn
lim from {z -> z sub 0} f left ( z right ) = f left ( z sub 0 right )