public virtual CovariateValuesCache Clone()
        {
            var clone = new CovariateValuesCache();

            _covariateValuesCache.Each(x => clone.Add(x.Clone()));
            return(clone);
        }
 public virtual void AddCovariate(string covariateName, IReadOnlyList <string> values) => CovariateValuesCache.Add(covariateName, values);