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: fiff_read_evoked_all.m
    path of file: ./repos/spm12/external/mne
    
    the code of the file until where you have to start completion: function [data] = fiff_read_evoked_all(fname)
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% [data] = fiff_read_evoked_all(fname)
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% Read all evoked data set (averages only)
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function [data] = fiff_read_evoked_all(fname)
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% [data] = fiff_read_evoked_all(fname)
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% Read all evoked data set (averages only)
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%   Author : Matti Hamalainen, MGH Martinos Center
%   License : BSD 3-clause
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%   Revision 1.6  2009/03/30 11:37:37  msh
%   Added copying of measurement info blocks from the original like in mne_browse_raw
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%   Revision 1.5  2008/03/28 13:35:51  msh
%   Accommodate evoked files from xplotter, which may have channel information
%   local to the evoked block
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%   Revision 1.4  2007/11/13 10:55:32  msh
%   Specify the second argument to all calls to the exist function
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%   Revision 1.3  2006/10/14 11:47:32  msh
%   Omitted listing of nepoch from the diagnostic output
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%   Revision 1.2  2006/10/14 11:39:58  msh
%   Fixed errors in fiff_read_evoked_all
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%   Revision 1.1  2006/10/04 20:12:37  msh
%   Added fiff_read_evoked_all
%   Modified fiff_pick_channels_evoked to handle multiple data sets
%   Added bad channel writing to fiff_write_evoked
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global FIFF;
if isempty(FIFF)
    FIFF = fiff_define_constants();
end