string signed$\_$extension$($string s$)\{$

$//$ you implement this one first

return $"0"$;

$\}$

int binary$\_$to$\_$decimal$\_$signed$($string s$)\{$

$//$ you implement this one third

return $0$;

$\}$

string decimal$\_$to$\_$binary$\_$signed$($int n$)\{$

$//$ you implement this one fourth

return $"0"$;

$\}$

string add$\_$binaries$\_$signed$($string b$1,$ string b$2)\{$

$//$ you implement this one fifth

return $"0"$;

$\}$

string twos$\_$complement$($string s$)\{$

$//$ you implement this one second

return $"0"$;

$\}$