ranges/ranges.go
func (r *InclusiveRange) Contains(value int) bool {
	// If we attempt to find the closest value, given
	// the start of the range and the step, we can check
	// if it is still the same number. If it hasn't changed,
	// then it is in the range.
	closest := r.closestInRange(value, r.start, r.End(), r.step)
	return closest == value
}
func (r *InclusiveRange) Contains(value int) bool {
	// If we attempt to find the closest value, given
	// the start of the range and the step, we can check
	// if it is still the same number. If it hasn't changed,
	// then it is in the range.
	closest := r.closestInRange(value, r.start, r.End(), r.step)
	return closest == value
}
// Contains returns true if the given value is a valid
// value within the value range.