def send(notice, promise)
      return will_not_deliver(notice) if @unsent.size >= @unsent.max

      @unsent << [notice, promise]
      promise
    end
def send(notice, promise)
      return will_not_deliver(notice) if @unsent.size >= @unsent.max

      @unsent << [notice, promise]
      promise
    end
Asynchronously sends a notice to Airbrake.

 @param [Airbrake::Notice] notice A notice that was generated by the
   library
 @return [Airbrake::Promise]