Popup the given menu and call the selected option.
MENU can be a keymap, an easymenu-style menu or a list of keymaps as for
`x-popup-menu'.
The menu is shown at the place where POSITION specifies. About
the form of POSITION, see `popup-menu-normalize-position'.
PREFIX is the prefix argument (if any) to pass to the command.
(fn MENU &optional POSITION PREFIX)