presto-main/src/main/java/io/prestosql/sql/analyzer/ExpressionAnalyzer.java/ExpressionAnalyzer/process
class ExpressionAnalyzer:        @Override
        public Type process(Node node, @Nullable StackableAstVisitorContext<Context> context)
        {
            if (node instanceof Expression) {
                // don't double process a node
                Type type = expressionTypes.get(NodeRef.of(((Expression) node)));
                if (type != null) {
                    return type;
                }
            }
            return super.process(node, context);
        }