SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 2)
    Identifier x
    Identifier y
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
   Function equals (children 1)
    ExpressionList (children 2)
     Function plus (children 1)
      ExpressionList (children 2)
       Identifier x
       Identifier y
     Literal UInt64_2
