SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function count (children 1)
     ExpressionList
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier null_in_1
   Function in (children 1)
    ExpressionList (children 2)
     Function tuple (children 1)
      ExpressionList (children 2)
       Identifier a
       Identifier b
     Literal Tuple_(NULL, NULL)
