Hello! One of the simplest (if not the simplest) examples of classical field theory is the complex scalar Klein-Gordon field, the relativistic version of the classical Schrodinger field. Now, Cadabra seems great for General Relativity, the DIrac field, the elecgtromagnetic field... but I see no clear treatment of complex scalars. It would be amazing if the tutorial would include a simple example with the Klein-Gordon field (i.e. how to find the Klein-Gordon equation given the action). This is done in the tutorial for the free classical Maxwell field, having another example would be great.