class_docstr: CAV class contains methods for concept activation vector (CAV).
  
  CAV represents semenatically meaningful vector directions in
  network's embeddings (bottlenecks).
class_docstr_tok: ["CAV","class","contains","methods","for","concept","activation","vector","(","CAV",")",".","CAV","represents","semenatically","meaningful","vector","directions","in","network","'s","embeddings","(","bottlenecks",")","."]
docstr: A key of this cav (useful for saving files).
  
  Args:
    concepts: set of concepts used for CAV
    bottleneck: the bottleneck used for CAV
    model_type: the name of model for CAV
    alpha: a parameter used to learn CAV
  
  Returns:
    a string cav_key
docstr_tok: ["A","key","of","this","cav","(","useful","for","saving","files",")",".","Args",":","concepts",":","set","of","concepts","used","for","CAV","bottleneck",":","the","bottleneck","used","for","CAV","model_type",":","the","name","of","model","for","CAV","alpha",":","a","parameter","used","to","learn","CAV","Returns",":","a","string","cav_key"]
code: def cav_key(concepts, bottleneck, model_type, alpha):
      """A key of this cav (useful for saving files).
  
      Args:
        concepts: set of concepts used for CAV
        bottleneck: the bottleneck used for CAV
        model_type: the name of model for CAV
        alpha: a parameter used to learn CAV
  
      Returns:
        a string cav_key
      """
      return (
          "-".join([str(c) for c in concepts])
          + "-"
          + bottleneck
          + "-"
          + model_type
          + "-"
          + str(alpha)
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os.path
  import pickle
  import numpy
  from six.moves import range
  from sklearn import linear_model
  from sklearn import metrics
  from sklearn.model_selection import train_test_split
  from tcav import utils
  import tensorflow
label_desc: Use image node_id 3 for calling the CAV obj's underlying member method code with example usage: obj.cav_key(concepts, bottleneck, model_type, alpha) and returns: unknown