code: func (st *TxnState) Get(k kv.Key) ([]byte, error) {
  	val, err := st.buf.Get(k)
  	if kv.IsErrNotFound(err) {
  		val, err = st.Transaction.Get(k)
  		if kv.IsErrNotFound(err) {
  			return nil, err
  		}
  	}
  	if err != nil {
  		return nil, err
  	}
  	if len(val) == 0 {
  		return nil, kv.ErrNotExist
  	}
  	return val, nil
  }
docs: // Get overrides the Transaction interface.