code: def begin(self):
      if wandb.run is None:
          raise wandb.Error(
              "You must call `wandb.init()` before calling `WandbHook`"
          )
      if self._summary_op is None:
          self._summary_op = merge_all_summaries()
      self._step = -1
  
file_path: wandb/wandb/integration/tensorflow/estimator_hook.py
imports: import tensorflow
  import wandb
  from wandb.sdk.lib import telemetry
label_desc: Use image node_id 2 for calling the WandbHook obj's underlying member method code with example usage: obj.begin() without return types