class_docstr: A `Callback` to handle the display of progress bars
class_docstr_tok: ["A","`","Callback","`","to","handle","the","display","of","progress","bars"]
code: def before_fit(self):
      assert hasattr(self.learn, "recorder")
      if self.create_mbar:
          self.mbar = master_bar(list(range(self.n_epoch)))
      if self.learn.logger != noop:
          self.old_logger, self.learn.logger = (
              self.logger,
              self._write_stats,
          )
          self._write_stats(self.recorder.metric_names)
      else:
          self.old_logger = noop
  
imports: from __future__ import annotations
  from ..basics import *
label_desc: Use image node_id 1 for calling the ProgressCallback obj's underlying member method code with example usage: obj.before_fit() without return types