code: def on_train_batch_begin(self, batch, logs=None):
      keys = list(logs.keys())
      print(
          "...Training: start of batch {}; got log keys: {}".format(
              batch, keys
          )
      )
  
imports: import numpy
  import keras
label_desc: Use image node_id 9 for calling the CustomCallback obj's underlying member method code with example usage: obj.on_train_batch_begin(batch, logs) without return types