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