code: func (h *blockHeaderStore) BlockLocatorFromHash(hash *chainhash.Hash) (
  	blockchain.BlockLocator, error) {
  
  	// Lock store for read.
  	h.mtx.RLock()
  	defer h.mtx.RUnlock()
  
  	return h.blockLocatorFromHash(hash)
  }
docs: // BlockLocatorFromHash computes a block locator given a particular hash. The
  // standard Bitcoin algorithm to compute block locators are employed.