private static MeasurementPeriodType Add(MeasurementPeriodType type)
 {
     _types.Add(type);
     return type;
 }
 protected bool Equals(MeasurementPeriodType other)
 {
     return string.Equals(_type, other._type);
 }
 private static MeasurementPeriodType Add(MeasurementPeriodType type)
 {
     _types.Add(type);
     return(type);
 }
 protected bool Equals(MeasurementPeriodType other)
 {
     return(string.Equals(_type, other._type));
 }
 static MeasurementPeriodType()
 {
     Hour  = Add(new MeasurementPeriodType('H'));
     Days  = Add(new MeasurementPeriodType('D'));
     Month = Add(new MeasurementPeriodType('M'));
 }