Forgot password functionality in shortcode

Hello,

I installed WP 4.3 and developed some shortcodes which take over login, register, edit profile, logout and forgot password functionalities.

My question: Shouldn’t retrieve_password() from wp-login.php function be defined in let’s say wp-includes/user.php so when I implement forgot password functionality I don’t have to copy&paste code from wp-login.php to my shortcode code?

If I do copy&paste would mean I “hardcode” forgot password functionality and I want to follow WP functionalities as much as possible.

Thanks,
Andy