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_convert_diffusion.m
    path of file: ./repos/automaticanalysis/aa_modules
    
    the code of the file until where you have to start completion: % Get diffusion dicom and convert nii.gz
% Converting Data to Analyze format and extracting the Gradient Directions
% extract the
    
function [aap resp]=aamod_convert_diffusion(aap,task,subjind,diffsessind,phaseencodeind)
resp='';

switch task
    case 'report'
    case 'doit'
        
        if exist('phaseencodeind','var')
            indices = [subjind diffsessind phaseencodeind];
            domain = 'diffusion_session_phaseencode_direction';
        else
            indices = [subjind diffsessind];
            domain = 'diffusion_session';
        end