class_docstr: Record of the values of multiple executions of all metrics.
  
  It contains `MetricHistory` instances for the metrics.
  
  Args:
      metrics: List of strings of the names of the metrics.
class_docstr_tok: ["Record","of","the","values","of","multiple","executions","of","all","metrics",".","It","contains","`","MetricHistory","`","instances","for","the","metrics",".","Args",":","metrics",":","List","of","strings","of","the","names","of","the","metrics","."]
code: def get_best_step(self, name):
      self._assert_exists(name)
      return self.metrics[name].get_best_step()
  
imports: import inspect
  import numpy
  import six
  from keras_tuner import protos
  from keras_tuner.api_export import keras_tuner_export
  from keras_tuner.backend import keras
label_desc: Use image node_id 9 for calling the MetricsTracker obj's underlying member method code with example usage: obj.get_best_step(name) and returns: self