PCreations/7617b3482e57.diff

## 7617b3482e57.diff
 -9,4 +9,8 @@ export class InMemoryBookRepository implements BookRepository {
     this.lastSavedBook = book;
     this.booksByTitle.set(book.title, book);
   }
+
+  async doesBookExist(title: string): Promise<boolean> {
+    return this.booksByTitle.has(title);
+  }
 }
	-9,4 +9,8 @@ export class InMemoryBookRepository implements BookRepository {
	this.lastSavedBook = book;
	this.booksByTitle.set(book.title, book);
	}
	+
	+ async doesBookExist(title: string): Promise<boolean> {
	+ return this.booksByTitle.has(title);
	+ }
	}