code: def prune(self):
      keys = [k for k in self.keys() if self[k] is None]
      for key in keys:
          self._dict.pop(key)
  
imports: from itertools import cycle
  from collections import OrderedDict
  from collections.abc import MutableMapping
  import paddle
label_desc: Use image node_id 8 for calling the InfoDict obj's underlying member method code with example usage: obj.prune() without return types