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