input: 
  from typing import Optional
  
  def create_html_form(action_url: str) -> str:
      """ Create an HTML form with a submit button that sends information to a Python program.
      The form should include an 'action' attribute pointing to the Python program URL.
      If no URL is provided, the form should still generate with an empty 'action'.
      >>> create_html_form("action.py")
      '<form action="action.py" method="post">\\n    <input type="submit" value="Submit">\\n</form>'
      >>> create_html_form("")
      '<form action="" method="post">\\n    <input type="submit" value="Submit">\\n</form>'
      """
      return f'<form action="{action_url}" method="post">\n    <input type="submit" value="Submit">\n</form>'
  
output:     
      return f'<form action="{action_url}" method="post">\n    <input type="submit" value="Submit">\n</form>'
  