Explain EXPLAIN QUERY TREE (children 2)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 2)
     Identifier a
     Identifier b
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Function numbers (children 1)
        ExpressionList (children 1)
         Literal UInt64_3
    ExpressionList (children 2)
     Identifier number (alias a)
     Function plus (alias b) (children 1)
      ExpressionList (children 2)
       Identifier number
       Identifier number
    ExpressionList (children 2)
     OrderByElement (children 1)
      Identifier a
     OrderByElement (children 1)
      Identifier b
 Identifier Null
