code: func (p *peer) RequestHeadersByNumber(origin uint64, amount int, skip int, reverse bool) error {
  	p.Log().Debug("Fetching batch of headers", "count", amount, "fromnum", origin, "skip", skip, "reverse", reverse)
  	return p2p.Send(p.rw, GetBlockHeadersMsg, &getBlockHeadersData{Origin: hashOrNumber{Number: origin}, Amount: uint64(amount), Skip: uint64(skip), Reverse: reverse})
  }
docs: // RequestHeadersByNumber fetches a batch of blocks' headers corresponding to the
  // specified header query, based on the number of an origin block.