input: Write a function to generate an HTML form with a submit button that sends information to a Python program when clicked. The function should return the HTML string representing the form.
  assert generate_html_form() == '<form action="action.py" method="post"><input type="submit" value="Submit"></form>'
output: def generate_html_form():
      return '<form action="action.py" method="post"><input type="submit" value="Submit"></form>'