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: BrainNet_spm_read_vols.m
    path of file: ./repos/EEGapp/EEGapp/custom_stuff/Brain_net/BrainNet_spm8_files
    
    the code of the file until where you have to start completion: function [Y,XYZ] = BrainNet_spm_read_vols(V,mask)
% Read in entire image volumes
% FORMAT [Y,XYZ] = spm_read_vols(V,mask)
% V    - vector of mapped image volumes to read in (from spm_vol)
% mask - implicit zero mask?
%
% Y    - 4D matrix of image data, fourth dimension indexes images
% XYZ  - 3xn matrix of XYZ locations returned (in mm)
%__________________________________________________________________________
%
% For image data types without a representation of NaN (see spm_type),
% implicit zero masking can be used. If mask is set, then zeros are
% treated as masked, and returned as NaN.
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging

% Andrew Holmes
% $Id: spm_read_vols.m 3663 2010-01-07 12:26:48Z guillaume $


    
function [Y,XYZ] = BrainNet_spm_read_vols(V,mask)
% Read in entire image volumes
% FORMAT [Y,XYZ] = spm_read_vols(V,mask)
% V    - vector of mapped image volumes to read in (from spm_vol)
% mask - implicit zero mask?
%
% Y    - 4D matrix of image data, fourth dimension indexes images
% XYZ  - 3xn matrix of XYZ locations returned (in mm)
%__________________________________________________________________________
%
% For image data types without a representation of NaN (see spm_type),
% implicit zero masking can be used. If mask is set, then zeros are
% treated as masked, and returned as NaN.
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging

% Andrew Holmes
% $Id: spm_read_vols.m 3663 2010-01-07 12:26:48Z guillaume $


%-Argument checks
%--------------------------------------------------------------------------
if nargin<2, mask = 0; end