[ EFraction
    NormalFrac
    (EGrouped
       [ EPhantom (EIdentifier "a")
       , ENumber "12"
       , EPhantom (EIdentifier "a")
       ])
    (ENumber "13")
, ESymbol Rel "="
, EFraction
    NormalFrac
    (ENumber "12")
    (EGrouped
       [ EPhantom (EIdentifier "a")
       , ENumber "13"
       , EPhantom (EIdentifier "a")
       ])
]