texmath-0.13.1.2: test/writer/eqn/msupBnest1.test
<<< native [ EIdentifier "x" , ESymbol Bin "+" , ESuper (EIdentifier "y") (EIdentifier "n") ] >>> eqn x + y sup n
<<< native [ EIdentifier "x" , ESymbol Bin "+" , ESuper (EIdentifier "y") (EIdentifier "n") ] >>> eqn x + y sup n