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: gen_key.m
    path of file: ./repos/Encryption-and-Image-Steganography-using-DWT
    
    the code of the file until where you have to start completion: function crypt_key = gen_key(user_key)
%NICHOLAS LAU
%000377939

    
function crypt_key = gen_key(user_key)
%NICHOLAS LAU
%000377939
%LAST EDITED: AUG. 20, 2016
%GENERATES A CRYPTO KEY BASED ON A USER KEY BY ADDING THE ASCII VALUES OF
%THE USER PASSWORD TOGETHER, THEN ADDING 27 AND DIVIDING BY 3. THE VALUE IS
%ROUNDED DOWN IF IT IS A DECIMAL NUMBER
crypt_key = [];
crypt_key = int16(user_key); %CHAR -> ASCII NUMBER
for(ii=1:size(user_key))
    crypt_key = sum(user_key');
end