public static QuantityTree <TT> ToQuantityTree <T, TI, TT>(this IEnumerable <T> items, Func <T, TI> func, Action <TI, QuantityTreeHelper <TT> > action)
{
var tree = new QuantityTree <TT>();
var helper = new QuantityTreeHelper <TT>(tree);
foreach (var item in items)
{
action(func(item), helper);
}
return(tree);
}
public QuantityTreeHelper(QuantityTree <T> tree) => Tree = tree;
