def range

      ids = @context.storage.ids('history')

      #p ids.sort == ids

      fm = DATE_REGEX.match(ids.first)[1]
      lm = DATE_REGEX.match(ids.last)[1]

      first = Time.parse("#{fm} 00:00:00 UTC")
      last = Time.parse("#{lm} 00:00:00 UTC") + 24 * 3600

      [ first, last ]
    end
def range

      ids = @context.storage.ids('history')

      #p ids.sort == ids

      fm = DATE_REGEX.match(ids.first)[1]
      lm = DATE_REGEX.match(ids.last)[1]

      first = Time.parse("#{fm} 00:00:00 UTC")
      last = Time.parse("#{lm} 00:00:00 UTC") + 24 * 3600

      [ first, last ]
    end
Returns an array [ most recent date, oldest date ] (Time instances).