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 __init__(self, metrics=None):
      # str -> MetricHistory
      self.metrics = {}
      self.register_metrics(metrics)
  
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 1 to create a new MetricsTracker object  with example: obj = MetricsTracker(metrics)