def duration
      segments = [self[:duration]/60]
      segments << (self[:duration] % 60 )
      segments.map {|t| t.to_s.rjust(2, '0')}.join(':')
    end
def duration
      segments = [self[:duration]/60]
      segments << (self[:duration] % 60 )
      segments.map {|t| t.to_s.rjust(2, '0')}.join(':')
    end
Formatted duration
 @return [String] duration formatted as time