public IPracticeTimeProgress SubtractMinutes(int minutes)
        {
            var time = CurrentTime - (minutes * 60);

            if (time < 0)
            {
                time = 0;
            }

            var progress = new PracticeTimeProgress(time, this.TargetTime, this.Weighting);

            return(progress);
        }
        public IPracticeTimeProgress SubstractSeconds(int seconds)
        {
            var time = CurrentTime - seconds;

            if (time < 0)
            {
                time = 0;
            }

            var progress = new PracticeTimeProgress(time, this.TargetTime, this.Weighting);

            return(progress);
        }