input: Write a function to create an HTML form with a submit button to send information to a Python program. The form should have the action attribute set to "action.py" and the method attribute set to "post". Return the HTML string of the form.
  
  assert create_html_form() == '<form action="action.py" method="post"><input type="submit" value="Submit"></form>'
output: def create_html_form():
      return '<form action="action.py" method="post"><input type="submit" value="Submit"></form>'