SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function less (children 1)
     ExpressionList (children 2)
      Function tuple (children 1)
       ExpressionList (children 3)
        Function toNullable (children 1)
         ExpressionList (children 1)
          Identifier number
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'a\'
        Identifier number
      Function tuple (children 1)
       ExpressionList (children 3)
        Identifier number
        Function materialize (children 1)
         ExpressionList (children 1)
          Literal \'a\'
        Identifier number
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Function numbers (children 1)
       ExpressionList (children 1)
        Literal UInt64_1