input: Write a function to generate an HTML table displaying information about the top 10 bestselling books in a specific genre from a SQLite database. The function should connect to the database 'books.db', execute a query to retrieve the top 10 books from the 'Books' table in the specified genre, and format the results into an HTML table.
  
  
  def generate_bestselling_books_html(genre):
      import sqlite3
      conn = sqlite3.connect('books.db')
      c = conn.cursor()
      c.execute('''SELECT title, author, genre, sales
                   FROM Books
                   WHERE genre=?
                   ORDER BY sales DESC
                   LIMIT 10''', (genre,))
      results = c.fetchall()
      html = '<table>'
      html += '<tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr>'
      for result in results:
          title, author, genre, sales = result
          html += f'<tr><td>{title}</td><td>{author}</td><td>{genre}</td><td>{sales}</td></tr>'
      html += '</table>'
      conn.close()
      return html
  
  assert generate_bestselling_books_html('Fantasy')
  assert generate_bestselling_books_html('Romance')
  assert generate_bestselling_books_html('Mystery')
  assert generate_bestselling_books_html('Science Fiction')
  
output: def generate_bestselling_books_html(genre):
      import sqlite3
      conn = sqlite3.connect('books.db')
      c = conn.cursor()
      c.execute('''SELECT title, author, genre, sales
                   FROM Books
                   WHERE genre=?
                   ORDER BY sales DESC
                   LIMIT 10''', (genre,))
      results = c.fetchall()
      html = '<table>'
      html += '<tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr>'
      for result in results:
          title, author, genre, sales = result
          html += f'<tr><td>{title}</td><td>{author}</td><td>{genre}</td><td>{sales}</td></tr>'
      html += '</table>'
      conn.close()
      return html