@classmethod
def _forced_interrupt(cls, signum):
    """Return True if `force_n` interrupts have been recieved in the past
        `force_timeout` seconds"""
    with cls._lock:
        signals_raised = cls._signals_raised.get(signum, [])
        return cls.force_n <= len(signals_raised
            ) and cls.force_timeout > signals_raised[-1][-1] - signals_raised[
            -cls.force_n][-1]
