When we have some custom implementation of Comparable, it's important
that we compare values exactly as 'lowBound <= a && a <= highBound'.
Make sure that evaluation order and compareTo calls match for
optimized and non-optimized case.
As of Kotlin 1.0 and 1.1, expression 'a in x .. y' is considered
equivalent to 'x.rangeTo(y).a', and should be evaluated in the following
order:
1. x
2. y
3. a
4. compare x with a
5. compare y with a (if needed)
Svyatoslav Kuzmich