input: Write a function to convert a list of book details into a list of dictionaries where each dictionary contains the title, author, and number of pages of each book.
  assert convert_books_to_dict([['The Hobbit', 'J.R.R. Tolkien', 295], ['The Catcher in the Rye', 'J.D. Salinger', 223]])==[{'title': 'The Hobbit', 'author': 'J.R.R. Tolkien', 'pages': 295}, {'title': 'The Catcher in the Rye', 'author': 'J.D. Salinger', 'pages': 223}]
  assert convert_books_to_dict([['1984', 'George Orwell', 328]])==[{'title': '1984', 'author': 'George Orwell', 'pages': 328}]
  assert convert_books_to_dict([])==[]
output: def convert_books_to_dict(books):
      return [{'title': book[0], 'author': book[1], 'pages': book[2]} for book in books] if books else []