message: Issue Numeric SUMMARIZE stats
  Tidy const reference.
diff: @@ -28,7 +28,7 @@ static unique_ptr<ParsedExpression> SummarizeCreateAggregate(const string &aggre
  }
  static unique_ptr<ParsedExpression> SummarizeCreateAggregate(const string &aggregate, string column_name,
  - Value modifier) {
  + const Value &modifier) {
  vector<unique_ptr<ParsedExpression>> children;
  children.push_back(make_unique<ColumnRefExpression>(move(column_name)));
  children.push_back(make_unique<ConstantExpression>(modifier));
  