code: def get_user_from_cookie(cookies, app_id, app_secret):
      
      cookie = cookies.get("fbsr_" + app_id, "")
      if not cookie:
          return None
      parsed_request = parse_signed_request(cookie, app_secret)
      if not parsed_request:
          return None
      try:
          result = GraphAPI().get_access_token_from_code(
              parsed_request["code"], "", app_id, app_secret
          )
      except GraphAPIError:
          return None
      result["uid"] = parsed_request["user_id"]
      return result
docs: Parses the cookie set by the official Facebook JavaScript SDK.
  
      cookies should be a dictionary-like object mapping cookie names to
      cookie values.
  
      If the user is logged in via Facebook, we return a dictionary with
      the keys "uid" and "access_token". The former is the user's
      Facebook ID, and the latter can be used to make authenticated
      requests to the Graph API. If the user is not logged in, we
      return None.
  
      Read more about Facebook authentication at
      https://developers.facebook.com/docs/facebook-login.