def convert_timedelta(duration):
    """
    Convert timedelta to H:M:S
    :param duration: datetime.timedelta object
    :return: string of H:M:S
    """
    days, seconds = duration.days, duration.seconds
    hours = days * 24 + seconds // 3600
    minutes = (seconds % 3600) // 60
    seconds = (seconds % 60)
    return '{0}h:{1}m:{2}s'.format(hours, minutes, seconds)