def previous_time(from=ZoTime.now)

      pt = nil
      zt = ZoTime.new(from.to_i - 1, @timezone)
      miny = from.year - NEXT_TIME_MAX_YEARS

      loop do

        pt = zt.dup

        fail RangeError.new(
          "failed to reach occurrence within " +
            "#{NEXT_TIME_MAX_YEARS} years for '#{original}'"
        ) if pt.year < miny

        unless date_match?(pt)
          zt.substract(pt.hour * 3600 + pt.min * 60 + pt.sec + 1)
          next
        end
        unless sub_match?(pt, :hour, @hours)
          zt.substract(pt.min * 60 + pt.sec + 1)
          next
        end
        unless sub_match?(pt, :min, @minutes)
          zt.substract(pt.sec + 1)
          next
        end
        unless sub_match?(pt, :sec, @seconds)
          zt.substract(prev_second(pt))
          next
        end

        break
      end

      pt
    end
def previous_time(from=ZoTime.now)

      pt = nil
      zt = ZoTime.new(from.to_i - 1, @timezone)
      miny = from.year - NEXT_TIME_MAX_YEARS

      loop do

        pt = zt.dup

        fail RangeError.new(
          "failed to reach occurrence within " +
            "#{NEXT_TIME_MAX_YEARS} years for '#{original}'"
        ) if pt.year < miny

        unless date_match?(pt)
          zt.substract(pt.hour * 3600 + pt.min * 60 + pt.sec + 1)
          next
        end
        unless sub_match?(pt, :hour, @hours)
          zt.substract(pt.min * 60 + pt.sec + 1)
          next
        end
        unless sub_match?(pt, :min, @minutes)
          zt.substract(pt.sec + 1)
          next
        end
        unless sub_match?(pt, :sec, @seconds)
          zt.substract(prev_second(pt))
          next
        end

        break
      end

      pt
    end
Returns the previous time the cronline matched. It's like next_time, but
 for the past.