def first(n = nil)
      occurrences = enumerate_occurrences(start_time).take(n || 1)
      n.nil? ? occurrences.first : occurrences
    end
def first(n = nil)
      occurrences = enumerate_occurrences(start_time).take(n || 1)
      n.nil? ? occurrences.first : occurrences
    end
Get the first n occurrences, or the first occurrence if n is skipped