SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function dictGetKeys (children 1)
     ExpressionList (children 3)
      Literal \'dict_valexpr\'
      Literal \'i32n\'
      Function CAST (children 1)
       ExpressionList (children 2)
        Literal NULL
        Literal \'Nullable(Int32)\'
