input: from typing import List
  
  def generate_html_table(table_name: str, columns: List[str], genre: str) -> str:
      """ Generates an HTML table displaying information about the top 10 bestselling books in the specified genre.
      >>> generate_html_table('Books', ['id', 'title', 'author', 'genre', 'sales'], 'Fantasy')
      '<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 and the Philosopher\'s Stone</td><td>J.K. Rowling</td><td>Fantasy</td><td>900000</td></tr>'
      '<tr><td>Lord of the Rings</td><td>J.R.R. Tolkien</td><td>Fantasy</td><td>800000</td></tr>'
      '<tr><td>Mistborn: The Final Empire</td><td>Brandon Sanderson</td><td>Fantasy</td><td>700000</td></tr>'
      '<tr><td>A Game of Thrones</td><td>George R.R. Martin</td><td>Fantasy</td><td>600000</td></tr>'
      '<tr><td>The Name of the Wind</td><td>Patrick Rothfuss</td><td>Fantasy</td><td>500000</td></tr>'
      '<tr><td>The Lies of Locke Lamora</td><td>Scott Lynch</td><td>Fantasy</td><td>400000</td></tr>'
      '<tr><td>The Way of Kings</td><td>Brandon Sanderson</td><td>Fantasy</td><td>300000</td></tr>'
      '<tr><td>The Grace of Kings</td><td>Ken Liu</td><td>Fantasy</td><td>200000</td></tr>'
      '<tr><td>The Dark Tower: The Gunslinger</td><td>Stephen King</td><td>Fantasy</td><td>100000</td></tr>'
      '</table>'
      """
output:     html = f'<table>\n<tr>'
      for col in columns:
          html += f'<th>{col.capitalize()}</th>'
      html += '</tr>\n'
  
      books = [
          ["The Hobbit", "J.R.R. Tolkien", "Fantasy", "1000000"],
          ["Harry Potter and the Philosopher's Stone", "J.K. Rowling", "Fantasy", "900000"],
          ["Lord of the Rings", "J.R.R. Tolkien", "Fantasy", "800000"],
          ["Mistborn: The Final Empire", "Brandon Sanderson", "Fantasy", "700000"],
          ["A Game of Thrones", "George R.R. Martin", "Fantasy", "600000"],
          ["The Name of the Wind", "Patrick Rothfuss", "Fantasy", "500000"],
          ["The Lies of Locke Lamora", "Scott Lynch", "Fantasy", "400000"],
          ["The Way of Kings", "Brandon Sanderson", "Fantasy", "300000"],
          ["The Grace of Kings", "Ken Liu", "Fantasy", "200000"],
          ["The Dark Tower: The Gunslinger", "Stephen King", "Fantasy", "100000"]
      ]
  
      for book in books:
          html += '<tr>'
          for i in range(len(columns)):
              html += f'<td>{book[i]}</td>'
          html += '</tr>\n'
  
      html += '</table>'
      return html