Helper class used in conjunction with
It has the tuples from the
as filtered by the
The tuples are sorted using a linked-list version of merge sort.
The sequence of n tuples for m variables is represented using
an array of length n where each element is an array of length m.
A possible future optimization would be to instead use m
different arrays of of length n. The advantage is that each
of the M arrays could have the "correct" type for each variable,
and so we avoid casts or boxing/unboxing.