$ include "seed7_05.s7i";

const type: Animal is new struct
    # ...
  end struct;

const type: Dog is sub Animal struct
    # ...
  end struct;

const type: Lab is sub Dog struct
    # ...
  end struct;

const type: Collie is sub Dog struct
    # ...
  end struct;

const type: Cat is sub Animal struct
    # ...
  end struct;