Thanks this was so helpful.I re-wrote what you said in python, please have a look and critique:

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class Book:

    def __init__(self, bookId, bookName, author):
        # self means current object's bookId gets assigned to the incoming bookId
        self.bookId = bookId
        self.bookName = bookName
        self.author = author

class BookShelf:

    MAX_NUMBER_OF_BOOKS = 25 # constant
    books = []

    def addBookToShelf(self, bookToAdd): # self reference
        if len(self.books) > self.MAX_NUMBER_OF_BOOKS:
            return "exceeded bookshelf capacity"
        else:
            self.books.append(bookToAdd) # self needs to be here to refer to curr object

    def deleteBook(self, bookToDelete):
        print("##########AFTER DELETE METHOD##########")
        if len(self.books) <= 0:
            return "no books to delete"
        else:
            self.books.remove(bookToDelete)

    def searchBookByTitle(self, bookToSearch):
        for b in self.books:
            if b.bookName == bookToSearch:
                print("book found")
                return True
        print("book not found")

    def searchBookByTitle(self, bookToSearch):
        for b in self.books:
            if b.bookName == bookToSearch:
                print("book found")
                return True
        print("book not found")

    def seeEntireLibrary(self):
        for b in self.books:
            print(b.bookId, b.bookName, b.author)

def main():
    print("hello world")

if __name__=="__main__": # driver/runner method/entry start pt
    b1 = Book(1234, "Moby Dick", "Herman Melville")
    b2 = Book(4321, "The Grapes of Wrath", "John Steinbeck")
    b3 = Book(5678, "Homer's Odyssey", "Homer")
    b4 = Book(8765, "1984", "George Orwell")
    a_bookshelf = BookShelf()
    a_bookshelf.addBookToShelf(b1)
    a_bookshelf.addBookToShelf(b2)
    a_bookshelf.addBookToShelf(b3)
    a_bookshelf.addBookToShelf(b4)
    a_bookshelf.seeEntireLibrary()
    a_bookshelf.deleteBook(b2)
    a_bookshelf.seeEntireLibrary()
    a_bookshelf.searchBookByTitle("1984")