Animating Views and Transitions - Swift UI Tutorials

I'm learning with this page on swift playgrounds, but I can't build successfully only this session. Swift Playgrounds 4 can't build this system?

Section 1 Add Hiking Data to the App https://developer.apple.com/tutorials/swiftui/animating-views-and-transitions

Animating Views and Transitions - Swift UI Tutorials
 
 
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