public static string ToPrettyString(this IThing thing) =>
thing.MapThing(
s => $"{s.Title} ({s.Subsections.Length.ToString()})",
ss => $"{ss.Title} ({ss.Clauses.Length.ToString()})",
c => $"{c.Title} ({c.Subclauses.Length.ToString()})",
sc => $"{sc.Title}"
);
public static IEnumerable <IThing> GetChildren(this IThing thing) =>
thing.MapThing(
s => s.Subsections as IEnumerable <IThing>,
ss => ss.Clauses as IEnumerable <IThing>,
c => c.Subclauses as IEnumerable <IThing>,
sc => EMPTY_THING
);