code: def _renew_by(name, window=None):
      '''
      Date before a certificate should be renewed
  
      :param name: Common Name of the certificate (DNS name of certificate)
      :param window: days before expiry date to renew
      :return datetime object of first renewal date
      '''
      expiry = _expires(name)
      if window is not None:
          expiry = expiry - datetime.timedelta(days=window)
  
      return expirf _renew_by(name, window=None):
      '''
      Date before a certificate should be renewed
  
      :param name: Common Name of the certificate (DNS name of certificate)
      :param window: days before expiry date to renew
      :return datetime object of first renewal date
      '''
      expiry = _expires(name)
      if window is not None:
          expiry = expiry - datetime.timedelta(days=window)
  
      return expiry
docs: Date before a certificate should be renewed
  
      :param name: Common Name of the certificate (DNS name of certificate)
      :param window: days before expiry date to renew
      :return datetime object of first renewal date