code: def from_json(json_string: str) -> Optional[dict[str, Any]]:
      """Reconstruct from a JSON string."""
      if json_string:
          return json.loads(json_string, object_hook=_obj_from_json)
      return None
  
file_path: lit/lit_nlp/lib/serialize.py
imports: import json
  from types import MappingProxyType
  from typing import Any, cast, Optional
  from lit_nlp.api import dtypes
  from lit_nlp.api import types
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: from_json(json_string) and returns: None, json