How would i synthesize a signal given this?

 function [xx, tt] = fourierSyn(ak, w0 , dur, fs)
% -----------------------------------------------------
% fourierSyn.m
% -----------------------------------------------------
% fourierSyn synthesizes a signal using Fourier series
% -----------------------------------------------------
% Syntax: [xx, tt] = fourierSyn(ak, w0 , dur, fs)
% ak = vector of 2N – 1 Fourier coefficients, N >= 1
% ak(1) is coefficient -N, ak(2N-1) is coefficient N
% ak(N) is coefficient 0 (DC)
% w0 = fundamental frequency in rad/sec
% dur = time duration of signal
% fs = sampling frequency (OPTIONAL: default is 10*fmax)
% xx = (vector of) samples of the synthesized signal
% tt = vector of time instants for t = 0 to t = dur
% -----------------------------------------------------
if( nargin < 4) % default fs
maxfreq = (length(ak) - 1)/2 * w0/(2*pi);
if maxfreq > 1
fs = 10*maxfreq;
else
fs = 10;
end
end

[Image Analyst]

Where is the rest of the code? xx and tt are not even created or returned. Is this a homework assignment where you were given partial code and expected to finish it?