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: ft_appendfreq.m
    path of file: ./repos/spm12/external/fieldtrip
    
    the code of the file until where you have to start completion: function [freq] = ft_appendfreq(cfg, varargin)


    
function [freq] = ft_appendfreq(cfg, varargin)

% FT_APPENDFREQ concatenates multiple frequency or time-frequency data structures
% that have been processed separately. If the input data structures contain different
% channels, it will be concatenated along the channel direction. If the channels are
% identical in the input data structures, the data will be concatenated along the
% repetition dimension.
%
% Use as
%  combined = ft_append