Function Dart_MapGetAt 

pub unsafe extern "C" fn Dart_MapGetAt(
    map: Dart_Handle,
    key: Dart_Handle,
) -> Dart_Handle

Gets the Object at some key of a Map.

May generate an unhandled exception error.

\param map A Map. \param key An Object.

\return The value in the map at the specified key, null if the map does not contain the key, or an error handle.