Adds a timeout callback. This callback gets called only once. If you want
periodic events you must reset the timeout in your callback.
This command returns an ID; you will need the ID
if you want to remove the timeout with VtRemoveTimeOut.
Options
-callbackcmd (C)
Sets the callback to call after the timeout interval has elapsed.
-intervalinteger NA)
Sets the timeout interval to integer milliseconds. For
example, 1000 = 1 second.