ENGLISH·COURSE API
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    SafariInstallSurface: "iphone" | "ipad" | "mac" | "none"

    The Apple surface a learner is on, as far as installing is concerned.

    Three rather than one, because the three need different guides: the taps differ, the surfaces they happen on differ in shape and position, and a Mac ends up with an icon in the Dock rather than on a home screen it does not have.