<<< native
[ EText
    TextNormal
    "Inline double down arrows, display style, thick line\160"
, EDelimited
    ""
    ""
    [ Left "\8659"
    , Right
        (EFraction
           NormalFrac
           (EGrouped
              [ EMathOperator "sin" , ESymbol Ord "\8289" , EIdentifier "\952" ])
           (EIdentifier "M"))
    , Left "\8659"
    ]
, EText TextNormal "\160the end."
]
>>> tex
\text{Inline double down arrows, display style, thick line~}\left. \Downarrow\frac{\sin\theta}{M}\Downarrow \right.\text{~the end.}