anchor.diff:  -record(state, {partition,
                   prepared_tx,
                   committed_tx,
  -                waiting_fsms,
                   active_txs_per_key,
                   write_set}).
   
  
positive.code: %%          partition: the partition that the vnode is responsible for.
  %%          prepared_tx: a list of prepared transactions.
  %%          committed_tx: a list of committed transactions.
  %%          waiting_fsms: a list of the read_fsms that are currently
  %%              waiting for each tx to finish.
  %%          active_txs_per_key: a list of the active transactions that
  %%              have updated a key (but not yet finished).
  %%          write_set: a list of the write sets that the transactions
  
negative.code: %%      1. notify all read_fsms that are waiting for this transaction to finish
  %%      2. clean the state of the transaction. Namely:
  %%      a. ActiteTxsPerKey,
  %%      b. PreparedTx
  %%
  clean_and_notify(TxId, Key, #state{active_txs_per_key=ActiveTxsPerKey,
                                     prepared_tx=PreparedTx,
  