private void Collate()
{
foreach (var group in progressions.GroupBy(x => x.stride))
{
foreach (var a in group)
{
foreach (var b in group)
{
if (a.Last() == b.First())
{
var collated = new Progression(group.Key);
collated.AddRange(a);
collated.AddRange(b.Skip(1));
collated.Sort();
collated.extended = a.extended || b.extended;
progressions.Add(collated);
progressions.Remove(a);
progressions.Remove(b);
}
}
}
}
}
