code: func (c *cluster) updateCoordinator(n *Node) bool { // nolint: unparam
  	c.mu.Lock()
  	defer c.mu.Unlock()
  	return c.unprotectedUpdateCoordinator(n)
  }
docs: // updateCoordinator updates this nodes Coordinator value as well as
  // changing the corresponding node's IsCoordinator value
  // to true, and sets all other nodes to false. Returns true if the value
  // changed.