SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 4)
   ExpressionList (children 2)
    Identifier id
    Identifier name
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier merge_tree_in_subqueries
   Function in (children 1)
    ExpressionList (children 2)
     Function tuple (children 1)
      ExpressionList (children 2)
       Identifier id
       Identifier name
     Literal Tuple_(UInt64_3, \'test3\')
   Set
