class_docstr: Hyper Parameter Tuning
class_docstr_tok: ["Hyper","Parameter","Tuning"]
docstr: Returns best idx in hyper-parameter tuning history.
docstr_tok: ["Returns","best","idx","in","hyper-parameter","tuning","history","."]
code: def best_idx(self):
      """Returns best idx in hyper-parameter tuning history."""
      return self._best_idx
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from xai.formatter.contents.base import Content
  from xai.formatter.writer.base import Writer
label_desc: Use image node_id 3 for calling the HyperParameterTuning obj's underlying member method code with example usage: obj.best_idx() and returns: self