SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function CAST (children 1)
     ExpressionList (children 2)
      Function map (children 1)
       ExpressionList (children 2)
        Literal \'a\'
        Function map (children 1)
         ExpressionList (children 2)
          Literal \'b\'
          Literal Array_[\'42\']
      Literal \'Map(String, Map(String, Array(FixedString(1000000))))\'
