Wordpress- hook to auto login after registration

Question: How can an user auto logged in after registration in wordPress? 
Answer: Using below hook/action/code, user will auto login after registration in wordPress.

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function _new_user_auto_log_in($user_id){   if(!is_user_logged_in()){     $secure_cookie = is_ssl();     $secure_cookie = apply_filters('secure_signon_cookie', $secure_cookie, array());     global $auth_secure_cookie;     $auth_secure_cookie = $secure_cookie;          wp_set_auth_cookie($user_id, true, $secure_cookie);     $user_info = get_userdata($user_id);     do_action('wp_login', $user_info->user_login, $user_info);     } } add_action('user_register', '_new_user_auto_log_in');