| treeMap.lean:8:59-8:69: error: failed to prove termination, possible solutions: | |
| - Use `have`-expressions to prove the remaining goals | |
| - Use `termination_by` to specify a different well-founded relation | |
| - Use `decreasing_by` to specify your own tactic for discharging this kind of goal | |
| name : String | |
| children : List TreeNode | |
| t : TreeNode | |
| ⊢ sizeOf t < 1 + sizeOf name + sizeOf children |