Senocular KeyObject class

Hello i got a question about this class.
it says:

Usage:
* var key:KeyObject = new KeyObject(stage);
* if (key.isDown(key.LEFT)) { … }

It works ok for UP, DOWN, LEFT, RIGHT, SPACE, etc…
But what if i want to use a key like “a” (keycode is 65).

key.isDown(key.65) doesn’t work.
key.isDown(65) doesn’t work.
key.isDown(Keyboard.A) doesn’t work (error 1119)
key.isDown(key.A) doesn’t work.

So, how can i do that?

thanks!