SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 2)
    Function toFixedString (alias str) (children 1)
     ExpressionList (children 2)
      Literal \'\'
      Literal UInt64_4
    Function empty (alias is_empty) (children 1)
     ExpressionList (children 1)
      Identifier str
