input: import requests
  
  def read_url(url: str) -> str:
      """ 
      Read the contents from a given URL and return the content as a string. If the request fails 
      (status code other than 200), return None.
      
      >>> read_url("https://www.example.com")
      '<!doctype html><html><head><title>Example Domain</title>...'
      
      >>> read_url("http://non-existent-url.com")
      None
      """
output:     response = requests.get(url)
      if response.status_code == 200:
          return response.text
      else:
          return None