code: func (db *DB) Get(key []byte, ro *opt.ReadOptions) (value []byte, err error) {
  	err = db.ok()
  	if err != nil {
  		return
  	}
  
  	se := db.acquireSnapshot()
  	defer db.releaseSnapshot(se)
  	return db.get(nil, nil, key, se.seq, ro)
  }
docs: // Get gets the value for the given key. It returns ErrNotFound if the
  // DB does not contains the key.
  //
  // The returned slice is its own copy, it is safe to modify the contents
  // of the returned slice.
  // It is safe to modify the contents of the argument after Get returns.