protected ExpressionValue(SubExpression subExpression) : base(subExpression)
 {
 }
 public NestedExpressionValue(SubExpression subExpression) : base(subExpression)
 {
 }
 public SubExpression(SubExpression subExpression) : this(subExpression.FocusConcepts, subExpression.Refinement)
 {
 }