presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/CanonicalizeExpressionRewriter.java/CanonicalizeExpressionRewriter/rewriteComparisonExpression
class CanonicalizeExpressionRewriter:        @Override
        public Expression rewriteComparisonExpression(ComparisonExpression node, Void context, ExpressionTreeRewriter<Void> treeRewriter)
        {
            // if we have a comparison of the form <constant> <op> <expr>, normalize it to
            // <expr> <op-flipped> <constant>
            if (isConstant(node.getLeft()) && !isConstant(node.getRight())) {
                node = new ComparisonExpression(node.getOperator().flip(), node.getRight(), node.getLeft());
            }

            return treeRewriter.defaultRewrite(node, context);
        }