TKinter IntVar() documentation

[Benjamin]

How does IntVar() works? It is not documented, so I tried to use it by
myself but it doesn't work well.

I've defined one for a checkbutton.
I want to connect thet value of IntVar() to a callback using trace

v = IntVar()
v.trace("rw",callback)

def callback(event):
    do things

burt it doesn't works, I have an error message every time I dor v.set(x) or
v.get()
"3 arguments, 1 argument expected"

There is a signal emitted by the IntVar but I don't connect it properly to
my callback function. Why?
Is the trace method the right one to connect a callback.

Thanks

Ben