SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Subquery (children 1)
     SelectWithUnionQuery (children 1)
      ExpressionList (children 1)
       SelectQuery (children 2)
        ExpressionList (children 1)
         Function CAST (children 1)
          ExpressionList (children 2)
           Literal NULL
           Literal \'Nullable(Nothing)\'
        Literal UInt64_0
