Explain EXPLAIN QUERY TREE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function minus (children 1)
      ExpressionList (children 2)
       Function sum (children 1)
        ExpressionList (children 1)
         Function plus (children 1)
          ExpressionList (children 2)
           Identifier float64
           Literal UInt64_2
       Function sum (children 1)
        ExpressionList (children 1)
         Function plus (children 1)
          ExpressionList (children 2)
           Identifier float64
           Literal UInt64_3
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test_table
