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Section 3.10 of the PhD describes two cases for which the extension can be helpful: 1. Sometimes the leader must step down. For example, it may need to reboot for maintenance, or it may be removed from the cluster. When it steps down, the cluster will be idle for an election timeout until another server times out and wins an election. This brief unavailability can be avoided by having the leader transfer its leadership to another server before it steps down. 2. In some cases, one or more servers may be more suitable to lead the cluster than others. For example, a server with high load would not make a good leader, or in a WAN deployment, servers in a primary datacenter may be preferred in order to minimize the latency between clients and the leader. Other consensus algorithms may be able to accommodate these preferences during leader election, but Raft needs a server with a sufficiently up-to-date log to become leader, which might not be the most preferred one. Instead, a leader in Raft can periodically check to see whether one of its available followers would be more suitable, and if so, transfer its leadership to that server. (If only human leaders were so graceful.) The patch here implements the extension and employs it automatically when a leader removes itself from a cluster.