def potential_next(current, base)
      candidate = super(current, base)
      return candidate if (base.year - candidate.year).to_i % @interval == 0

      years = ((base.year - candidate.year).to_i % @interval)

      (candidate + years.years).beginning_of_year
    end
def potential_next(current, base)
      candidate = super(current, base)
      return candidate if (base.year - candidate.year).to_i % @interval == 0

      years = ((base.year - candidate.year).to_i % @interval)

      (candidate + years.years).beginning_of_year
    end
closest valid date