callback create [script] [-option value...]
Create a callback function and returns its ID. The function is called until it returns another code than ok (e.g. return -code break) or until it is deleted with the delete subcommand.
Options
type: integer or "idle" (default: idle)
If interval is an integer, script is called every interval milliseconds. If its "idle" script is called whenever there are no other events pending.
type: integer (default: 0)
Priority with which this callback is handled. Negativ values mean lower priority than normal, positiv values mean higher priority than normal.
callback delete [ID]
Deletes the callback function with the ID ID.