input: import requests
  
  def read_url(url: str) -> str:
      """ Reads the contents from a given URL. Returns the text if status code is 200, otherwise returns None.
      >>> read_url('https://www.example.com')
      '<html>...</html>'
      >>> read_url('https://www.nonexistenturl.com')
      None
      """
output:     response = requests.get(url)
      if response.status_code == 200:
          return response.text
      else:
          return None