code: def is_nullable(object_schema: dict, key: str) -> bool:
      sub = object_schema["properties"][key]
      if isinstance(sub, bool):
          return sub
      assert isinstance(sub, dict), f"expected dict but got {sub}"
      if "const" in sub:
          return False
      if "enum" in sub:
          return None in sub["enum"]
      if "type" in sub:
          if isinstance(sub["type"], list):
              return "null" in sub["type"]
          return bool(sub["type"] == "null")
      return False
  
imports: import argparse
  import json
  import os
  import re
  import sys
  from typing import Callable, List, Optional, Tuple, TypeVar, Union
label_desc: Use image node_id 5 for calling a global function with example usage: is_nullable(object_schema, key) and returns: False, sub, False, unknown, bool, unknown