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: aamod_structuralstats.m
    path of file: ./repos/automaticanalysis/aa_modules
    
    the code of the file until where you have to start completion: function [aap,resp] = aamod_structuralstats(aap, task, subjind)
% AAMOD_STRUCTURALSTATS Get total tissue class volumes and TIV for segmented images.
%
% Get volume in mm^3 of GM, WM, CSF, and total intracranial volume (TIV).
%
% input streams:    native_grey
%                   native_white
%                   native_csf
%
% output stream:    structuralstats

resp='';

switch task
    case 'domain'
        resp = 'subject';
    case 'report'

    
function [aap,resp] = aamod_structuralstats(aap, task, subjind)
% AAMOD_STRUCTURALSTATS Get total tissue class volumes and TIV for segmented images.
%
% Get volume in mm^3 of GM, WM, CSF, and total intracranial volume (TIV).
%
% input streams:    native_grey
%                   native_white
%                   native_csf
%
% output stream:    structuralstats

resp='';

switch task
    case 'domain'
        resp = 'subject';
    case 'report'
        resp = 'Get statistics on segmented structural images.';
    case 'doit'
        [junk, SPMtool] = aas_cache_get(aap,'spm');
        
        streams = aas_getstreams(aap,'input');
        S.parts.desc = {'1=grey matter','2=white matter','3=csf'};
        
        %% Conventional
        for k=1:3
            img = aas_getfiles_bystream(aap, subjind, streams{k});

            V = spm_vol(img);
            Y = spm_read_vols(V);
            spacedesc = spm_imatrix(V.mat);
            volume = prod(abs(spacedesc(7:9)));
            Y = Y(~isnan(Y));
            S.parts.vox(k) = sum(Y(:));
            S.parts.mm3(k) = S.parts.vox(k)*volume;
        end