input: Write a function to generate an HTML form with a submit button that sends information to a specified Python program. The function should take the path to the Python program as an argument and return the complete HTML form as a string.
  assert generate_html_form("action.py")=='<form action="action.py" method="post"><input type="submit" value="Submit"></form>'
  assert generate_html_form("process.py")=='<form action="process.py" method="post"><input type="submit" value="Submit"></form>'
  assert generate_html_form("")==''
  assert generate_html_form("submit.py")=='<form action="submit.py" method="post"><input type="submit" value="Submit"></form>'
  assert generate_html_form(None)==''
output: def generate_html_form(program_path):
      if not program_path:
          return ''
      return f'<form action="{program_path}" method="post"><input type="submit" value="Submit"></form>'