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: bf_load.m
    path of file: ./repos/spm/toolbox/DAiSS
    
    the code of the file until where you have to start completion: function BF = bf_load(file, fields)
% Load BF data into memory with just the requested fields
%__________________________________________________________________________

% Vladimir Litvak
% Copyright (C) 2012-2023 Wellcome Centre for Human Neuroimaging

    
function BF = bf_load(file, fields)
% Load BF data into memory with just the requested fields
%__________________________________________________________________________

% Vladimir Litvak
% Copyright (C) 2012-2023 Wellcome Centre for Human Neuroimaging


% get filename
%-------------------------------------------------------------------------
if nargin == 0
    [file, sts] = spm_select(1, '^BF.mat$', 'Select BF.mat file');
    if ~sts, BF = []; return; end