input: from typing import List, Tuple
  
  def generate_html_table(genre: str, book_table: Tuple[str, str, str, int]) -> str:
      """
      Generate an HTML table displaying information about the top 10 bestselling books in a specific genre.
      The input is assumed to be pre-sorted in descending order based on sales.
  
      Args:
      - genre: The genre of the books (e.g., 'Fantasy').
      - book_table: A list of tuples, where each tuple contains (title, author, genre, sales).
  
      Returns:
      - An HTML string representing the table.
  
      >>> generate_html_table('Fantasy', [('The Hobbit', 'J.R.R. Tolkien', 'Fantasy', 1000000), ('Harry Potter', 'J.K. Rowling', 'Fantasy', 900000)])
      '<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>900000</td></tr></table>'
      """
      html = '<table>'
      html += '<tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr>'
  
      for title, author, genre, sales in book_table:
          html += f'<tr><td>{title}</td><td>{author}</td><td>{genre}</td><td>{sales}</td></tr>'
  
      html += '</table>'
      return html
output:     html = '<table>'
      html += '<tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr>'
  
      for title, author, genre, sales in book_table:
          html += f'<tr><td>{title}</td><td>{author}</td><td>{genre}</td><td>{sales}</td></tr>'
  
      html += '</table>'
      return html