+///
+/// User needs to notify implementors of ManyChannelMonitor when a new block is connected or
+/// disconnected using their `block_connected` and `block_disconnected` methods. However, rather
+/// than calling these methods directly, the user should register implementors as listeners to the
+/// BlockNotifier and call the BlockNotifier's `block_(dis)connected` methods, which will notify
+/// all registered listeners in one go.