consumer.go
func (c *Consumer) MarkPartitionOffset(topic string, partition int32, offset int64, metadata string) {
	if sub := c.subs.Fetch(topic, partition); sub != nil {
		sub.MarkOffset(offset, metadata)
	}
}
func (c *Consumer) MarkPartitionOffset(topic string, partition int32, offset int64, metadata string) {
	if sub := c.subs.Fetch(topic, partition); sub != nil {
		sub.MarkOffset(offset, metadata)
	}
}
// MarkPartitionOffset marks an offset of the provided topic/partition as processed.
// See MarkOffset for additional explanation.