infix operator ?? { associativity right precedence 131 } Declarations func ?? <T>(_: T?, defaultValue: () throws -> T) Declaration func ??<T>(optional: T?, @autoclosure defaultValue: () throws -> T) -> T func ?? <T>(_: T?, defaultValue: () throws -> T?) Declaration func ??<T>(optional: T?, @autoclosure defaultValue: () throws -> T?) -> T?