How to use tutorial

Red squiggles will appear in the editor if the code does not compile or if your code has identified invalid data. The invalid data will also be highlighted in table.

Both the code and the data can be edited. If you make changes to the code, remember to click "Run" to recompile your changes.

Go ahead and edit Joe's age in the table so that it is not negative.

Next: Your first assertion

User(id) {
  id: Number
  name: String
  age: Number
  assert age >= 0
}