/// <summary>
        /// Set a fallback formatter for durations over a given limit.
        /// </summary>
        ///
        /// <param name="fallback_0">the fallback formatter to use, or null</param>
        /// <returns>this BasicDurationFormatterFactory</returns>
        public virtual DurationFormatterFactory SetFallback(DateFormatter fallback_0)
        {
            bool doReset = (fallback_0 == null) ? this.fallback != null : !fallback_0
                           .Equals(this.fallback);

            if (doReset)
            {
                this.fallback = fallback_0;
                Reset();
            }
            return(this);
        }