input: 
  def generate_bestselling_book_table(genre: str) -> str:
      """ Generate an HTML table displaying information about the top 10 bestselling books in the given genre.
      >>> generate_bestselling_book_table('Fantasy')
      '<table><tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr><tr><td>Book1</td><td>Author1</td><td>Fantasy</td><td>1000</td></tr><tr><td>Book2</td><td>Author2</td><td>Fantasy</td><td>900</td></tr><tr><td>Book3</td><td>Author3</td><td>Fantasy</td><td>800</td></tr><tr><td>Book4</td><td>Author4</td><td>Fantasy</td><td>700</td></tr><tr><td>Book5</td><td>Author5</td><td>Fantasy</td><td>600</td></tr><tr><td>Book6</td><td>Author6</td><td>Fantasy</td><td>500</td></tr><tr><td>Book7</td><td>Author7</td><td>Fantasy</td><td>400</td></tr><tr><td>Book8</td><td>Author8</td><td>Fantasy</td><td>300</td></tr><tr><td>Book9</td><td>Author9</td><td>Fantasy</td><td>200</td></tr><tr><td>Book10</td><td>Author10</td><td>Fantasy</td><td>100</td></tr></table>'
      """
  
output:     table = "<table><tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr>"
      for i in range(1, 11):
          table += f"<tr><td>Book{i}</td><td>Author{i}</td><td>{genre}</td><td>{1100 - i * 100}</td></tr>"
      table += "</table>"
      return table