a user wants a more efficient search capability. (It is more
efficient than calling equivalent_patterns() over and over in a
loop, because it doesn't repeatedly re-canonicalize the search
pattern.)
as part of canonicalizing comparison expressions. This
required adding a new comparison expression transformer callback
for leaf-node comparison expression objects, and updating all
existing comparison transformers to work (it affected all/most
of them). The observation expression transformer which actually
does the comparison canonicalization was updated to also perform
this special canonicalization step.
Michael Chisholm