input: 
  import requests
  
  def read_url(url: str) -> str:
      """Read the contents from a given URL and return the content as a string, 
      or None if the request fails.
      
      >>> read_url('https://example.com')
      'Example Domain\\nThis domain is for use in illustrative examples in documents. You may use this\\n  \\n          domain in literature without prior coordination or asking for permission.\\n\\n  \\n          More information...\\n'
      
      >>> read_url('https://nonexistenturl.com')
      None
      """
      r = requests.get(url)
      if r.status_code == 200:
          return r.text
      else:
          return None
  
output:     r = requests.get(url)
      if r.status_code == 200:
          return r.text
      else:
          return None