code: def freeze_keys(self):
      if self.__frozen_keys:
          return
      self.__frozen_keys = True
      for v in self.values():
          if isinstance(v, FrozenKeyMunch):
              v.freeze_keys()
  
file_path: sacred/sacred/settings.py
imports: import platform
  from sacred.utils import SacredError
  import sacred.optional
  from munch import Munch
  from packaging import version
label_desc: Use image node_id 1 for calling the FrozenKeyMunch obj's underlying member method code with example usage: obj.freeze_keys() without return types