This is the correct interpretation. Imagine an infinite time line, with a marker moving across the line at the speed of time. Every time increment is called, t

This is the correct interpretation. Imagine an infinite time line, with a marker moving across the line at the speed of time. Every time increment is called, that marker is saved on the timeline. When getCountInLastX is called, one must return the number of marks on the timeline from the current time to the current time minus X.