[OS X Emacs] how to undefine a Command-key

[Pete Siemsen]

I don't like that in Aquamacs, Command-H is bound to ns-do-hide- 
emacs.  I sometimes hit Command-H by accident, so I'd like it to do  
nothing.  I tried putting this in my startup file, to no effect.

        (define-key osx-key-mode-map (kbd "A-h") nil)

What's the right syntax?

-- Pete