code: def run_exception_handlers(exception)
        status = true
        exception_handlers.each do |handler|
          status &&= begin
            handler.call(exception)
          rescue
            nil
          end
        end
        Isimud.retry_failures.nil? ? status : Isimud.retry_failures
      end
docs: Call each of the exception handlers declared by #on_exception.
   @param [Exception] exception
   @return [Boolean] true if message should be requeued, false otherwise