class_docstr: Update a graph of training and validation loss
class_docstr_tok: ["Update","a","graph","of","training","and","validation","loss"]
code: def before_fit(self):
      self.run = not hasattr(self.learn, "lr_finder") and not hasattr(
          self, "gather_preds"
      )
      if not (self.run):
          return
      self.nb_batches = []
      assert hasattr(self.learn, "progress")
  
imports: from __future__ import annotations
  from ..basics import *
label_desc: Use image node_id 1 for calling the ShowGraphCallback obj's underlying member method code with example usage: obj.before_fit() without return types