Predicate function used to evaluate condition matches.
Remarks
A leaf operator's predicate answers true or false: it sees a blank only as null, and
only with Ignore Blank off; never a value its selector did not read. A combinator's
predicate answers an Answer, since
a child's selector may have answered NotApplicable. A caller tests === true.
Predicate function used to evaluate condition matches.
Remarks
A leaf operator's predicate answers
trueorfalse: it sees a blank only asnull, and only with Ignore Blank off; never a value its selector did not read. A combinator's predicate answers an Answer, since a child's selector may have answered NotApplicable. A caller tests=== true.