doubleint1.test

<<< native
[ ESubsup (ESymbol Op "\8748") (ENumber "0") (ENumber "1")
, EIdentifier "f"
, EDelimited "(" ")" [ Right (EIdentifier "x") ]
, ESpace (1 % 9)
, ESymbol Ord "\8518"
, EIdentifier "x"
]
>>> tex
\iint_{0}^{1}f(x)\mspace{2mu}\mathbb{d}x