'Update the DB instance\'s status information by making a call to fetch
the current instance attributes from the service.
:type validate: bool
:param validate: By default, if EC2 returns no data about the
instance the update method returns quietly.  If the
validate param is True, however, it will raise a
ValueError exception if no data is returned from EC2.'

def update(self, validate=False):

    rs = self.connection.get_all_dbinstances(self.id)
    if (len(rs) > 0):
        for i in rs:
            if (i.id == self.id):
                self.__dict__.update(i.__dict__)
    elif validate:
        raise ValueError(('%s    is    not    a    valid    Instance    ID' % self.id))
    return self.status
