class_docstr: Like weakref.WeakKeyDictionary, but compares objects with "is".
class_docstr_tok: ["Like","weakref.WeakKeyDictionary",",","but","compares","objects","with","``","is","''","."]
code: def __len__(self):
      # Iterate, discarding old weak refs
      return len(list(self._storage))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import weakref
label_desc: Use image node_id 2 for calling the ObjectIdentityWeakKeyDictionary obj's underlying member method code with example usage: obj.__len__() and returns: len