public PlanType transformExpressionsUp(Function<Expression, Expression> rule) {
        return transformExpressionsUp(PartialFunction.fromFunction(rule));
    }
Runs [[transformUp]] with `rule` on all expressions present in this query operator.

@param rule the rule to be applied to every expression in this operator.
indexr-query-opt/src/main/java/io/indexr/query/plan/QueryPlan.java