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: spm_dcm_fnirs_specify.m
    path of file: ./repos/spm/toolbox/dcm_fnirs
    
    the code of the file until where you have to start completion: function DCM = spm_dcm_fnirs_specify(SPMf)
% Specify inputs of a DCM for fNIRS
% FORMAT [DCM] = spm_dcm_nirs_specify(SPMf)
%
% SPMf - SPM filename(s)
%
% DCM  - DCM structure (see spm_dcm_ui)
%__________________________________________________________________________

% Will Penny & Sungho Tak
% Copyright (C) 2015-2022 Wellcome Centre for Human Neuroimaging

%--------------------------------------------------------------------------
%-Interactive window
Finter = spm_figure('GetWin','Interactive');
bcolor = get(Finter,'color');
WS     = spm('WinScale');
dx     = 20;


    
function DCM = spm_dcm_fnirs_specify(SPMf)
% Specify inputs of a DCM for fNIRS
% FORMAT [DCM] = spm_dcm_nirs_specify(SPMf)
%
% SPMf - SPM filename(s)
%
% DCM  - DCM structure (see spm_dcm_ui)
%__________________________________________________________________________

% Will Penny & Sungho Tak
% Copyright (C) 2015-2022 Wellcome Centre for Human Neuroimaging

%--------------------------------------------------------------------------
%-Interactive window
Finter = spm_figure('GetWin','Interactive');
bcolor = get(Finter,'color');
WS     = spm('WinScale');
dx     = 20;

spm_input('Specify DCM for fNIRS:...  ',1,'d');

%--------------------------------------------------------------------------
% Get SPM.mat files
if ~nargin || isempty(SPMf)
    [SPMf, sts] = spm_select([1 Inf],'^SPM\.mat$','Select SPM.mat');
    if ~sts, DCM = []; return; end