Mini Project: Library Management System

class Book:
    def __init__(self, title, author, isbn):
        self.title = title
        self.author = author
        self.isbn = isbn
        self.available = True
    
    def __str__(self):
        status = "Available" if self.available else "Checked Out"
        return f"'{self.title}' by {self.author} [{status}]"

class Member:
    def __init__(self, name, member_id):
        self.name = name
        self.member_id = member_id
        self.borrowed = []
    
    def __str__(self):
        return f"{self.name} (ID: {self.member_id}, Books: {len(self.borrowed)})"

class Library:
    def __init__(self, name):
        self.name = name
        self.books = []
        self.members = []
    
    def add_book(self, book):
        self.books.append(book)
        print(f"  Added: {book.title}")
    
    def register_member(self, member):
        self.members.append(member)
        print(f"  Registered: {member.name}")
    
    def checkout(self, member, book):
        if book.available:
            book.available = False
            member.borrowed.append(book)
            print(f"  {member.name} borrowed '{book.title}'")
        else:
            print(f"  '{book.title}' is not available!")
    
    def return_book(self, member, book):
        if book in member.borrowed:
            book.available = True
            member.borrowed.remove(book)
            print(f"  {member.name} returned '{book.title}'")
    
    def display_catalog(self):
        print(f"\n=== {self.name} Catalog ===")
        for book in self.books:
            print(f"  {book}")

# Demo
lib = Library("City Library")
b1 = Book("Python Crash Course", "Eric Matthes", "978-1")
b2 = Book("Clean Code", "Robert Martin", "978-2")
b3 = Book("The Pragmatic Programmer", "Hunt & Thomas", "978-3")

lib.add_book(b1)
lib.add_book(b2)
lib.add_book(b3)

alice = Member("Alice", "M001")
bob = Member("Bob", "M002")
lib.register_member(alice)
lib.register_member(bob)

lib.display_catalog()

print("\n--- Transactions ---")
lib.checkout(alice, b1)
lib.checkout(bob, b2)
lib.checkout(bob, b1)  # Already checked out!

lib.display_catalog()

lib.return_book(alice, b1)
lib.display_catalog()