code: func (u *ID) Addr() (updateAddr storage.Address) {
  	serializedData := make([]byte, idLength)
  	var cursor int
  	u.Feed.binaryPut(serializedData[cursor : cursor+feedLength])
  	cursor += feedLength
  
  	eid := u.Epoch.ID()
  	copy(serializedData[cursor:cursor+lookup.EpochLength], eid[:])
  
  	hasher := hashPool.Get().(hash.Hash)
  	defer hashPool.Put(hasher)
  	hasher.Reset()
  	hasher.Write(serializedData)
  	return hasher.Sum(nil)
  }
docs: // Addr calculates the feed update chunk address corresponding to this ID