input: from typing import List
  
  def generate_html_table_for_top_books(genre: str, book_data: List[tuple]) -> str:
      """ Generate an HTML table displaying information about the top 10 bestselling books in a specific genre.
      The function takes a genre and a list of tuples where each tuple contains the title, author, genre, and sales of a book.
      Each tuple should follow the order: title (string), author (string), genre (string), sales (int).
      >>> generate_html_table_for_top_books('Fantasy', [('The Hobbit', 'J.R.R. Tolkien', 'Fantasy', 1000000), ('Harry Potter', 'J.K. Rowling', 'Fantasy', 2000000)])
      '<table><tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr><tr><td>The Hobbit</td><td>J.R.R. Tolkien</td><td>Fantasy</td><td>1000000</td></tr><tr><td>Harry Potter</td><td>J.K. Rowling</td><td>Fantasy</td><td>2000000</td></tr></table>'
      """
output:     html_table = '<table><tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr>'
      for book in book_data:
          if book[2] == genre:
              html_table += f'<tr><td>{book[0]}</td><td>{book[1]}</td><td>{book[2]}</td><td>{book[3]}</td></tr>'
      html_table += '</table>'
      return html_table