Related to this it might be good to figure out exactly how the Debug and Display traits are supposed to be used. One option is that Debug is always derived, or should always give full information. And that the Display trait should print the output nicely formatted, but can omit some information that is not relevant to the user. For example in an LTS we can apply the labels to the transitions, and then omit the exact indices of them (this information is then not relevant, but Debug keeps that). Then we introduce functions for printing only the size (a summary) etc.