Tell SwiftUI what to do when elements in theview are deleted.
// list data from environment object
// (assume `data` is the environment object)
ForEach(data.creatures) { creature in
CreatureRow(creature: creature)
}
// โญ๏ธ when elements in the ForEach view are deleted
.onDelete { indexSet in
/// โข SwiftUI passes a set of indices to the closure
/// thatโs relative to the dynamic viewโs underlying collection of data.
// โญ๏ธ delete corresponding items from the underlying collection of data
data.creatures.remove(atOffsets: indexSet)
}