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_DesRep.m
    path of file: ./repos/bspm/thirdparty/spm12
    
    the code of the file until where you have to start completion: function varargout = spm_DesRep(varargin)
% Design reporting utilities
% FORMAT varargout = spm_DesRep(action,varargin)
%
% spm_D
    
function function, the first argument is an action  )
%( string, specifying the particular action function to take.          )
%
% FORMAT h = spm_DesRep('DesRepUI',SPM)
% Setup "design" menu for design reporting.
% SPM    - structure containing design details. Required fields are:
%
% .xX    - design matrix structure
%          (See spm_fmri_spm_ui.m & spm_spm.m for formats)
% .xY.P  - (char or cellstr) array of filenames
% .xY.VY - array of file handles (from spm_fmri_spm_ui.m)
% .xM    - Masking structure
% .xC    - Covariate definition structure (not fMRI)
%          (see spm_spm_ui.m for format)
% .Sess  - fMRI session structure (not needed if not fMRI)
%          (see spm_fmri_spm_ui.m for format)
% .xsDes - Design description structure
%          (see spm_fmri_spm_ui.m for details)
% .swd   - SPM working directory - directory where configuration file resides
%          [defaults to empty]
% .SPMid - (recommend