def add_properties(self, filename):
        """
        Add properties to config based on filename replacing previous values.
        :param filename: str path to YAML file to pull top level properties from
        """
        filename = os.path.expanduser(filename)
        if os.path.exists(filename):
            with open(filename, 'r') as yaml_file:
                self.update_properties(yaml.safe_load(yaml_file))