Vim: list free keybindings

Is there some way to list unused keybinds? I guess if the answer is no, it would be a good feature-request (especially for these undecided types like myself).

Edit: To make it more precise, I know you can list bindings with:

:map
:nmap
开发者_JAVA技巧:imap

FFI see:

:help map-modes

and manually check whether given binding is used by typing e.g.:

:help Ctrl-w
:help ^w

FFI see:

:help map

To my knowledge there is no way to list the unused key-bindings (this would be impossible because there is an infinite number of them).

But if you want to go the other way around you can type:

:map

:imap 

to list the user defined key-bindings.

Also if you type

:help index

you can check if some key-binding is already assigned to a function in vim.