Explain EXPLAIN QUERY TREE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function plus (children 1)
      ExpressionList (children 2)
       Function multiply (children 1)
        ExpressionList (children 2)
         Literal UInt64_2
         Function count (children 1)
          ExpressionList (children 1)
           Identifier uint64
       Function sum (children 1)
        ExpressionList (children 1)
         Identifier uint64
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test_table
