- * Implementations **must** ensure that updates are successfully applied and persisted upon method
- * completion. If an update fails with a [`PermanentFailure`], then it must immediately shut down
- * without taking any further action such as persisting the current state.
- *
- * If an implementation maintains multiple instances of a channel's monitor (e.g., by storing
- * backup copies), then it must ensure that updates are applied across all instances. Otherwise, it
- * could result in a revoked transaction being broadcast, allowing the counterparty to claim all
- * funds in the channel. See [`ChannelMonitorUpdateErr`] for more details about how to handle
- * multiple instances.
- *
- * [`PermanentFailure`]: ChannelMonitorUpdateErr::PermanentFailure