# File lib/ice_cube/builders/ical_builder.rb, line 47
    def self.ical_duration(duration)
      hours = duration / 3600; duration %= 3600
      minutes = duration / 60; duration %= 60
      repr = ''
      repr << "#{hours}H" if hours > 0
      repr << "#{minutes}M" if minutes > 0
      repr << "#{duration}S" if duration > 0
      "PT#{repr}"
    end