private static Expression <Func <bool> > getValueExpression(
INotifyCollectionChanged source,
Expression <Func <TSourceItem, bool> > predicateExpression)
{
Expression <Func <TSourceItem, bool> > negativePredicateExpression = getNegativePredicateExpression(predicateExpression);
return(() => !source.AnyComputing(negativePredicateExpression).Value);
}
