SwiftUI tutorial Animating view and transitions section 3/4/5 Hike folder issue

In section 4/5 of the Animating and transitions tutorial, the steps show code that looks like it is missing pieces of the code that is contained in the actual hike folder. These pieces include :

#Preview {

    VStack {

        HikeView(hike: ModelData().hikes[0])

            .padding()

        Spacer()

    }

}

at the bottom of the HikeView file , and

func rangeOfRanges<C: Collection>(_ ranges: C) -> Range<Double>

    where C.Element == Range<Double> {

    guard !ranges.isEmpty else { return 0..<0 }

    let low = ranges.lazy.map { $0.lowerBound }.min()!

    let high = ranges.lazy.map { $0.upperBound }.max()!

    return low..<high

}

func magnitude(of range: Range<Double>) -> Double {

    range.upperBound - range.lowerBound

}

#Preview {

    let hike = ModelData().hikes[0]

    return Group {

        HikeGraph(hike: hike, path: \.elevation)

            .frame(height: 200)

        HikeGraph(hike: hike, path: \.heartRate)

            .frame(height: 200)

        HikeGraph(hike: hike, path: \.pace)

            .frame(height: 200)

    }

}

located at the bottom of the HikeGraph file

when these code pieces are used properly, the code runs fine. Though, the HikeGraph preview does look a bit jumbled. I don't know if this is an error for not including these or if I used the code improperly but somehow got the correct result.