Need a simple structural query language (expressable in JSON). PipelineRunsService.list_annotations: https://github.com/TangleML/tangle/blob/26456ad3d56190cfec6d68d3517c135759c8d735/cloud_pipelines_backend/api_server_sql.py#L284 Predicates: * key1 [not] exists * key1 value [not] equals value1 * key1 value is [not] in set: value1, value2 * key1 value [not] contains substr1 * and