input: Write a function to create an HTML table of contents from a list of strings.
  assert generate_toc(["Introduction", "Chapter 1", "Chapter 2", "Conclusion"]) == '<ul><li>Introduction</li><li>Chapter 1</li><li>Chapter 2</li><li>Conclusion</li></ul>'
  assert generate_toc(["Item 1", "Item 2", "Item 3"]) == '<ul><li>Item 1</li><li>Item 2</li><li>Item 3</li></ul>'
  assert generate_toc(["Section A", "Section B"]) == '<ul><li>Section A</li><li>Section B</li></ul>'
output: def generate_toc(items):
      toc = '<ul>'
      for item in items:
          toc += f'<li>{item}</li>'
      toc += '</ul>'
      return toc