presto-main/src/main/java/io/prestosql/sql/analyzer/ExpressionAnalyzer.java/Visitor/Visitor
class Visitor:        public Visitor(Scope baseScope, WarningCollector warningCollector)
        {
            this.baseScope = requireNonNull(baseScope, "baseScope is null");
            this.warningCollector = requireNonNull(warningCollector, "warningCollector is null");
        }