def GetSystemRootCACertChain(self):
    """Load system supplied root CA certs.

    Returns:
      str, all x509 root ca certs, or '' if none can be found
    """
    try:
      f = open(settings.ROOT_CA_CERT_CHAIN_PEM_PATH, 'r')
      contents = f.read()
    except (__HOLE__, IOError):
      contents = None  # root CA cert chain is optional
    if contents:
      logging.debug('Got Root CA Cert Chain: %s', contents)
      return contents
    else:
      logging.warning('Root CA Cert Chain was EMPTY!')
      return ''
dataset/ETHPy150Open google/simian/src/simian/client/client.py/HttpsAuthClient.GetSystemRootCACertChain