Call FUNCTION once for each event binding in KEYMAP.
FUNCTION is called with two arguments: the event that is bound, and
the definition it is bound to. The event may be a character range.
If KEYMAP has a parent, the parent's bindings are included as well.
This works recursively: if the parent has itself a parent, then the
grandparent's bindings are also included and so on. (fn FUNCTION KEYMAP)