def timestr(seconds):
    """
    Convert seconds into seconds, minutes or hours
    """
    
    if seconds < 60:
        return '{:.2f} seconds'.format(seconds)
    
    minutes = seconds / 60
    if minutes < 60:
        return '{:.2f} minutes'.format(minutes)
    
    hours = minutes / 60
    return '{:.2f} hours'.format(hours)