[求助]如何绑定C-1

我想要将C-1绑定到某一个函数:

(keymap-global-set "C-1" 'xxx)

但是,重启emacs后会有Error:

error: Key sequence C - 1 starts with non-prefix key 

请问怎么解决,谢谢。

要先解除默认的绑定

(defun test1 ()
  (interactive)
  (message "hello"))
(global-unset-key (kbd "C-1"))
(global-set-key (kbd "C-1") #'test1)