public PlanType transformAllExpressions(PartialFunction<Expression, Expression> rule) {
        return transform(new PartialFunction<PlanType, PlanType>() {
            @Override
            public boolean isDefinedAt(PlanType x) {
                return x instanceof QueryPlan;
            }

            @Override
            public PlanType apply(PlanType plan) {
                return plan.transformExpressions(rule);
            }
        });
    }
Returns the result of running [[transformExpressions]] on this node
and all its children.
indexr-query-opt/src/main/java/io/indexr/query/plan/QueryPlan.java