code: func (g *Getter) Get(addr chunk.Address) (ch chunk.Chunk, err error) {
  	out, err := g.db.get(g.mode, addr)
  	if err != nil {
  		if err == leveldb.ErrNotFound {
  			return nil, chunk.ErrChunkNotFound
  		}
  		return nil, err
  	}
  	return chunk.NewChunk(out.Address, out.Data), nil
  }
docs: // Get returns a chunk from the database. If the chunk is
  // not found chunk.ErrChunkNotFound will be returned.
  // All required indexes will be updated required by the
  // Getter Mode.