code: def schedule_exception_at(unixtime, exception, target):
      
      if not isinstance(target, compat.greenlet):
          raise TypeError("can only schedule exceptions for greenlets")
      if target.dead:
          raise ValueError("can't send exceptions to a dead greenlet")
      schedule_at(unixtime, target)
      state.to_raise[target] = exception
docs: schedule a greenlet to have an exception raised at a unix timestamp
  
      :param unixtime: when to raise the exception in the target
      :type unixtime: int or float
      :param exception: the exception to raise in the greenlet
      :type exception: Exception
      :param target: the greenlet that should receive the exception
      :type target: greenlet