input: Write a function to fetch and print book titles from a given URL category using urllib and json.
  assert fetch_book_titles("https://www.example.com/books/category/Computer Science") == ["Introduction to Algorithms", "Artificial Intelligence: A Modern Approach", "The Art of Computer Programming"]
  assert fetch_book_titles("https://www.example.com/books/category/Mathematics") == ["Calculus", "Linear Algebra", "Discrete Mathematics"]
  assert fetch_book_titles("https://www.example.com/books/category/Physics") == ["Classical Mechanics", "Quantum Physics", "Thermodynamics"]
output: import urllib.request
  import json
  
  def fetch_book_titles(url):
      with urllib.request.urlopen(url) as response:
          data = json.loads(response.read().decode())
      return [book['title'] for book in data['books']]