def queue_retry_delay_proc(proc=nil)
        if proc
          @queue_retry_delay_proc = proc
        else # accessor
          @queue_retry_delay_proc
        end
      end
Returns or assigns queue retry_delay_proc for this job

@example
queue_retry_delay_proc lambda { |min_retry_delay, num_retries| min_retry_delay + (num_retries ** 2) }
@klass.queue_retry_delay_proc # => lambda { |min_retry_delay, num_retries| min_retry_delay + (num_retries ** 2) }