'Return True if the device exists in the namespace.'

def exists(self):

    orig_log_fail_as_error = self.get_log_fail_as_error()
    self.set_log_fail_as_error(False)
    try:
        return bool(self.link.address)
    except RuntimeError:
        return False
    finally:
        self.set_log_fail_as_error(orig_log_fail_as_error)
