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: nutmeg2fieldtrip.m
    path of file: ./repos/bspm/thirdparty/spm12/external/fieldtrip
    
    the code of the file until where you have to start completion: function [data, mri, 
    
function and scripts
ft_revision = '$Id$';
ft_nargin   = nargin;
ft_nargout  = nargout;

% do the general setup of the function
ft_defaults
ft_preamble init
ft_preamble debug
ft_preamble provenance
ft_preamble trackconfig

if ~isstruct(fileorstruct) && exist(fileorstruct,'file')
  structin=load(fileorstruct);
elseif isstruct(fileorstruct)
  structin=fileorstruct;
elseif ~isstruct(fileorstruct)
  ft_error('please enter either a structure (beam or nuts) or filename containing either beam or nuts')
end