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: bspm_harvest_timeseries.m
    path of file: ./repos/bspm/utilities
    
    the code of the file until where you have to start completion: function ts_roi = bspm_harvest_timeseries(images, roi, method)
% BSPM_HARVEST_TIMESERIES
%
%   USAGE: bspm_harvest_timeseries(images, roi, method)
% 
%   images = filenames from which to harvest
%   roi = filename of region of interest

    
function ts_roi = bspm_harvest_timeseries(images, roi, method)
% BSPM_HARVEST_TIMESERIES
%
%   USAGE: bspm_harvest_timeseries(images, roi, method)
% 
%   images = filenames from which to harvest
%   roi = filename of region of interest
%   method = 0: mean, >0: pca (value specifies number of dimensions)
%

% ----------------------- Copyright (C) 2014 -----------------------
%	Author: Bob Spunt
%	Affilitation: Caltech
%	Email: spunt@caltech.edu
%
%	$Revision Date: Aug_20_2014

if nargin<3, mfile_showhelp; return; end