NewMempool instantiates and initializes node mempool.

ErrAlreadyExists transaction with the same txid already exists in mempool.

ErrAlreadyExistsInBlockchain transaction with the same txid already exists in blockchain.

ErrNullifierExists nullifier(s) already exists in the mempool state.

Mempool is a storage for the chain transactions that are valid according to the current chain state and can be included in the next block.

TxDesc encapsulates both tx raw and meta data.

Pool represents a transaction pool of the verified txs only.