code: func (f *FilterHeaderStore) readHeader(height uint32) (*chainhash.Hash, error) {
  	seekDistance := uint64(height) * 32
  
  	rawHeader, err := f.readRaw(seekDistance)
  	if err != nil {
  		return nil, err
  	}
  
  	return chainhash.NewHash(rawHeader)
  }
docs: // readHeader reads a single filter header at the specified height from the
  // flat files on disk.