+ """Add to self.history if and only if not same value as newest one.
+
+ Note that we wait one micro-second, as timestamp comparison to check
+ most recent elements only goes up to that precision.
+
+ Also note that we don't check against .newest because that may make us
+ compare value against .default even if not set. We want to be able to
+ explicitly set .default as the first element.
+ """
+ sleep(0.00001)