You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test243.m
    path of file: ./repos/SuiteSparse/GraphBLAS/Test
    
    the code of the file until where you have to start completion: function test243
%TEST243 test GxB_Vector_Iterator

% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2023, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0


    
function test243
%TEST243 test GxB_Vector_Iterator

% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2023, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0

rng ('default') ;
[~, ~, ~, types, ~, ~] = GB_spec_opsall ;
types = types.all ;
ntypes = length (types) ;

n = 30 ;
GB_builtin_complex_set (true) ;

% scalar_in is dense and all zero
scalar_in.matrix = sparse (0) ;
scalar_in.pattern = true ;

desc.inp0 = 'tran' ;

for k = 1:(ntypes + 1)

    if (k == ntypes + 1)
        % user-defined double complex
        GB_builtin_complex_set (false) ;
        type = 'double complex'  ;
        fprintf ('\nComplex (UDT):\n') ;
    else
        % built-in types
        type = types {k}  ;
        fprintf ('\n%s:\n', type) ;
    end