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: dti_euler_pipe.m
    path of file: ./repos/md-dmri/methods/dti_euler
    
    the code of the file until where you have to start completion: function fn = dti_euler_pipe(s, paths, opt)
% function fn = dti_euler_pipe(s, paths, opt)

    
function fn = dti_euler_pipe(s, paths, opt)
% function fn = dti_euler_pipe(s, paths, opt)
%
% s     - input structure
% paths - either a pathname or a path structure (see mdm_paths)
% opt   - (optional) options that drive the pipeline
%
% fn    - a cell array with filenames to generated nii files

if (nargin < 2), paths = fileparts(s.nii_fn); end