class_docstr: Outputs summary data by writing event files to a log directory.
  
  TODO(#4581): This API should be considered EXPERIMENTAL and subject to
  backwards-incompatible changes without notice.
docstr: See `Output`.
docstr_tok: ["See","`","Output","`","."]
code: def emit_scalar(
      self,
      *,
      plugin_name,
      tag,
      data,
      step,
      wall_time,
      tag_metadata=None,
      description=None,
  ):
      """See `Output`."""
      # TODO(#4581): cache summary metadata to emit only once.
      summary_metadata = summary_pb2.SummaryMetadata(
          plugin_data=summary_pb2.SummaryMetadata.PluginData(
              plugin_name=plugin_name, content=tag_metadata
          ),
          summary_description=description,
          data_class=summary_pb2.DataClass.DATA_CLASS_SCALAR,
      )
      tensor_proto = tensor_util.make_tensor_proto(data)
      event = event_pb2.Event(wall_time=wall_time, step=step)
      event.summary.value.add(
          tag=tag, tensor=tensor_proto, metadata=summary_metadata
      )
      self._ev_writer.add_event(event)
  
file_path: tensorboard/tensorboard/summary/_output.py
imports: from tensorboard.compat.proto import event_pb2
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.summary.writer import event_file_writer
  from tensorboard.util import tensor_util
  import abc
label_desc: Use image node_id 2 for calling the DirectoryOutput obj's underlying member method code with example usage: obj.emit_scalar() without return types