class_docstr: Dataset for Annotations used in MMF
  
  TODO: Update on docs sprint
code: def _load_json(self, path):
      with PathManager.open(path, "r") as f:
          data = json.load(f)
      self.metadata = data.get("metadata", {})
      self.data = data.get("data", [])
  
      if len(self.data) == 0:
          raise RuntimeError("Dataset is empty")
  
file_path: mmf/mmf/datasets/databases/annotation_database.py
imports: import json
  import numpy
  import torch
  from mmf.utils.file_io import PathManager
  from mmf.utils.general import get_absolute_path
label_desc: Use image node_id 5 for calling the AnnotationDatabase obj's underlying member method code with example usage: obj._load_json(path) without return types