'Unique hash for this object
:return: ``str``
The hash is a function of an SHA1 hash of prefix, the object\'s ID and
its driver which means that it should be unique between all
interfaces.
TODO : to review
>>> from libcloud.compute.drivers.dummy import DummyNodeDriver
>>> driver = DummyNodeDriver(0)
>>> vif = driver.create_interface()
>>> vif.get_uuid()
\'d3748461511d8b9b0e0bfa0d4d3383a619a2bb9f\'
Note, for example, that this example will always produce the
same UUID!'

def get_uuid(self):

    hashstring = ('%s:%s:%s' % (self.uuid_prefix, self.id, self.driver.type))
    return hashlib.sha1(b(hashstring)).hexdigest()
