public Library()
{
IComparer <Book> comparer = new BookComparer();
this.books = new SortedSet <Book>(comparer);
}
public Library(params Book[] booksArray) // IEnumerable<Book> booksArray
{
IComparer <Book> comparer = new BookComparer();
this.books = new SortedSet <Book>(booksArray, comparer);
}
