presto-main/src/main/java/io/prestosql/sql/analyzer/Scope.java/Scope/withOuterQueryParent
class Scope:        public Builder withOuterQueryParent(Scope parent)
        {
            checkArgument(!this.parent.isPresent(), "parent is already set");
            this.parent = Optional.of(parent);
            this.queryBoundary = true;
            return this;
        }