i am just starting python and i have

cont = GameLogic.getCurrentController()
own = cont.getOwner()
can = cont.getSensor() 
#can is a near sensor for an object with "savepoint" property

if can.isPositive():
   #here i have the rest

the can sensor does not work

You should include name of desired sensor as parameter in method getSensor:

can = own.getSensor('mySensor')

or whatever name it has.

i have that already sorry i forgot to write that