ChangesetLess returns true if c[i] < c[j].

CorrectionLess returns true when comparing corrections.

DebugKeyMapMap debug prints the results from ChangedGroups.

New is a constructor for a Differ.

NewCompat is a constructor that uses the new pkg/diff2 system instead of pkg/diff.

Correlation stores a difference between two records.

Differ is an interface for computing the difference between two zones.

Changeset stores many Correlation.