class_docstr: Abstract client class to manage cached state for neighbor examples.
  
  This abstract class will be implemented as a client to lookup and update
  values from a cache service.
docstr: Returns the feature name of the key.
docstr_tok: ["Returns","the","feature","name","of","the","key","."]
code: def key_feature_name(self):
      """Returns the feature name of the key."""
      return self._key_feature_name
  
file_path: neural-structured-learning/research/carls/neighbor_cache_client.py
imports: import abc
  import six
label_desc: Use image node_id 4 for calling the NeighborCacheClient obj's underlying member method code with example usage: obj.key_feature_name() and returns: self