class LibraryCollection{
    constructor(capacity){
        this.capacity=capacity;
        this.books=[];
    }
    addBook (bookName, bookAuthor){

        for (let i = 0; i < this.books.length; i++) {
           if( this.books[i] == null){
            throw new Error("Not enough space in the collection.")
           }else{
            let book={
                bookName:bookName,
                bookAuthor:bookAuthor,
                payed: false,
            }

            this.books.push(book)

            return "The {bookName}, with an author {bookAuthor}, collect.";
        }
    }


    }

    payBook( bookName ) {
        if(!this.books.some(x => x.bookName == bookName)){
            throw new Error(`${bookName} is not in the collection.`)
        }
        if (this.books.some(x => x.payed=)) {

        }
    }
    removeBook(bookName) {

    }
    getStatistics(bookAuthor){

    }
}