input: Write a python function to create a Book object and return its string representation.
  assert create_book("1984", "George Orwell", 1949) == "1984 by George Orwell (1949)"
  assert create_book("To Kill a Mockingbird", "Harper Lee", 1960) == "To Kill a Mockingbird by Harper Lee (1960)"
  assert create_book("The Great Gatsby", "F. Scott Fitzgerald", 1925) == "The Great Gatsby by F. Scott Fitzgerald (1925)"
output: def create_book(title, author, year):
      class Book:
          def __init__(self, title, author, year):
              self.title = title
              self.author = author
              self.year = year
  
          def __str__(self):
              return f"{self.title} by {self.author} ({self.year})"
      
      book = Book(title, author, year)
      return str(book)