Resume the previously suspended terminal device TTY.
The terminal is opened and reinitialized. Frames that are on the
suspended terminal are revived.
It is an error to resume a terminal while another terminal is active
on the same device.
This function runs `resume-tty-functions' after resuming the terminal.
The functions are run with one arg, the id of the resumed terminal
`resume-tty' does nothing if it is called on a device that is not
TTY may be a terminal object, a frame, or nil (meaning the selected frame's terminal). (fn &optional TTY)