class_docstr: Tracks training progress and visualizes it.
  For example, use it to track the training and validation loss and accuracy
  and plot them.
class_docstr_tok: ["Tracks","training","progress","and","visualizes","it",".","For","example",",","use","it","to","track","the","training","and","validation","loss","and","accuracy","and","plot","them","."]
code: def __getitem__(self, metric):
      return Metric(self, metric)
  
imports: import math
  import random
  import io
  import itertools
  import time
  import datetime
  import pickle
  import numpy
  import matplotlib.pyplot
  import matplotlib
  from .None import utils
label_desc: Use image node_id 5 for calling the History obj's underlying member method code with example usage: obj.__getitem__(metric) and returns: Metric