def _process_config(config):
    """
    Make sure config object has required values

    """
    required_fields = [
        "account_sid",
        "auth_token",
        "from_phone",
        "to_phone",
        ]

    for field in required_fields:
        if field not in config:
            raise ValueError("required field {} not found in config file".format(field))

    return config