input: def read_url(url: str) -> str:
      """Read the contents from a given URL.
      >>> read_url("https://example.com")
      '<!doctype html>\n<html>\n<head>\n<title>Example Domain</title>...'
      >>> read_url("https://invalid-url.com")
      None
      """
      response = requests.get(url)
      if response.status_code == 200:
          return response.text
      else:
          return None
output:     import requests