A function to display all Functional keys F1 ~ F12

Sometimes I will forget which functional key do what in script map.
So I want a function to display all functional keys from F1 to F12.
The maps content can from command :verbose map <F1>.
Those content can be displayed in any style, like a new window, or same buffer with :echomsg.
I just want to display those key binds detail at once.
I do not case how you archive this function. (maybe the the better the more simple it is).

Thanks guys.
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