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: iss_dec.m
    path of file: ./repos/audio-steganography-algorithms/01-Spread-Spectrum/02-Improved-Spread-Spectrum
    
    the code of the file until where you have to start completion: function str = iss_dec(signal, L_msg, L_min)
%ISS_DEC decoding function for Improved Spread Spectrum.
%

    
function str = iss_dec(signal, L_msg, L_min)
%ISS_DEC decoding function for Improved Spread Spectrum.
%
%   INPUTS VARIABLES
%       signal : Stego audio signal
%       L_msg  : Length of message
%       L_min  : Minimum value for segment length
%
%   OUTPUTS VARIABLES
%       str    : Retrieved text message
%
%   20170420 - Kadir Tekeli (kadir_tekeli@hotmail.com)

if nargin < 3
    L_min = 1024;
end