def METHOD_NAME(self, run_name, new_metadata):
    if run_name not in self.run_metadata:
        self.run_metadata[run_name] = {}
    for k, v in new_metadata.items():
        self.run_metadata[run_name][k] = v
    # Serialize the data to ensure it is json serializable
    json.dumps(self.run_metadata[run_name])