_isDayInsideSelectionRange(timestamp) {
      // No selection at all (or not in range selection mode)
      if (this.selectionMode !== _CalendarSelectionMode.default.Range || !this.selectedDates.length) {
        return false;
      }
      // Only one date selected - the user is hovering with the mouse or navigating with the keyboard to select the second one
      if (this.selectedDates.length === 1 && this._secondTimestamp) {
        return isBetween(timestamp, this.selectedDates[0], this._secondTimestamp);
      }
      // Two dates selected - stable range
      return isBetween(timestamp, this.selectedDates[0], this.selectedDates[1]);
    }
Tells if the day is inside a selection range (light blue).
@param { number } timestamp
@returns { boolean }
@private