是否有一种方法可以注释大量的代码?

I'm trying to comment out a large piece of code in a program but it's too difficult to do it manually. Is there a program to do it for me? (making such program doesn't seem hard anyway) Also, I'm using emacs. Does emacs have such a function? (or an emacs Lisp file at least?)I'm trying to comment out a large piece of code