Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Function sum (children 1)
      ExpressionList (children 1)
       Function plus (alias i) (children 1)
        ExpressionList (children 2)
         Literal UInt64_1
         Identifier uint64
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test_table
    Function greater (children 1)
     ExpressionList (children 2)
      Identifier i
      Literal UInt64_0
