class_docstr: Often it is desirable to prevent the mutation of
  a default dict after its initial construction, such
  as to prevent mutation during iteration.
  
  >>> dd = FreezableDefaultDict(list)
  >>> dd[0].append('1')
  >>> dd.freeze()
  >>> dd[1]
  []
  >>> len(dd)
  1
code: def freeze(self):
      self._frozen = lambda key: self.default_factory()
  
file_path: catboost/contrib/tools/python3/src/Lib/importlib/metadata/_collections.py
imports: import collections
label_desc: Use image node_id 2 for calling the FreezableDefaultDict obj's underlying member method code with example usage: obj.freeze() without return types