RCLConsensus::Adaptor::getPrevLedger

Get the ID of the previous ledger/last closed ledger(LCL) on the network.

uint256
getPrevLedger(
    uint256 ledgerID,
    RCLCxLedger const& ledger,
    ConsensusMode mode);

Name	Description
`ledgerID`	ID of previous ledger used by consensus
`ledger`	Previous ledger consensus has available
`mode`	Current consensus mode

The id of the last closed network

ledgerID may not match ledger.id() if we haven't acquired the ledger matching ledgerID from the network