input: from typing import List
  
  def generate_html_table(table_name: str, columns: List[str], genre: str) -> str:
      """ Generate an HTML table displaying the top 10 bestselling books in a specific genre.
      The table name and columns are provided, and the genre is specified. The data is retrieved from a database.
      >>> generate_html_table('Books', ['title', 'author', 'genre', 'sales'], 'Fantasy')
      '<table><tr><th>Title</th><th>Author</th><th>Genre</th><th>Sales</th></tr></table>'
      """
output:     html = f'<table><tr><th>{table_name}</th></tr>'
      for col in columns:
          html += f'<th>{col.capitalize()}</th>'
      html += '</tr></table>'
      return html