keras/src/callbacks/progbar_logger.py/ProgbarLogger/on_epoch_begin
class ProgbarLogger:    def on_epoch_begin(self, epoch, logs=None):
        self._reset_progbar()
        self._maybe_init_progbar()
        if self.verbose and self.epochs > 1:
            io_utils.print_msg(f"Epoch {epoch + 1}/{self.epochs}")