code: func (b *rpcSyncMgr) LocateHeaders(locators []*chainhash.Hash, hashStop *chainhash.Hash) []wire.BlockHeader {
  	return b.server.chain.LocateHeaders(locators, hashStop)
  }
docs: // LocateBlocks returns the hashes of the blocks after the first known block in
  // the provided locators until the provided stop hash or the current tip is
  // reached, up to a max of wire.MaxBlockHeadersPerMsg hashes.
  //
  // This function is safe for concurrent access and is part of the
  // rpcserverSyncManager interface implementation.