See setup_intent.usage and Reusing Cards.
Use on_session if you intend to only reuse the payment method when your customer is present in your checkout flow.
Use off_session if your customer may or may not be in your checkout flow.
Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
Returns an array containing the constants of this enum type, in the order they're declared.