class_docstr: A `Callback` that keeps track of the best value in `monitor`.
class_docstr_tok: ["A","`","Callback","`","that","keeps","track","of","the","best","value","in","`","monitor","`","."]
docstr: Compare the last value to the best up to now
docstr_tok: ["Compare","the","last","value","to","the","best","up","to","now"]
code: def after_epoch(self):
      "Compare the last value to the best up to now"
      val = self.recorder.values[-1][self.idx]
      if self.comp(val - self.min_delta, self.best):
          self.best, self.new_best = val, True
      else:
          self.new_best = False
  
imports: from __future__ import annotations
  from ..basics import *
  from .progress import *
  from .fp16 import MixedPrecision
label_desc: Use image node_id 3 for calling the TrackerCallback obj's underlying member method code with example usage: obj.after_epoch() without return types