code: func (h *blockHeaderStore) FetchHeaderByHeight(height uint32) (*wire.BlockHeader, error) {
  	// Lock store for read.
  	h.mtx.RLock()
  	defer h.mtx.RUnlock()
  
  	// For this query, we don't need to consult the index, and can instead
  	// just seek into the flat file based on the target height and return
  	// the full header.
  	header, err := h.readHeader(height)
  	if err != nil {
  		return nil, err
  	}
  
  	return &header, nil
  }
docs: // FetchHeaderByHeight attempts to retrieve a target block header based on a
  // block height.
  //
  // NOTE: Part of the BlockHeaderStore interface.