class_docstr: FileWriter for test.
  
  TensorFlow FileWriter uses TensorFlow's Protobuf Python binding
  which is largely discouraged in TensorBoard. We do not want a
  TB.Writer but require one for testing in integrational style
  (writing out event files and use the real event readers).
code: def add_meta_graph(self, meta_graph_def, global_step=None):
      if isinstance(meta_graph_def, meta_graph_pb2.MetaGraphDef):
          tf_meta_graph_def = tf.compat.v1.MetaGraphDef.FromString(
              meta_graph_def.SerializeToString()
          )
      else:
          tf_meta_graph_def = meta_graph_def
  
      super().add_meta_graph(
          meta_graph_def=tf_meta_graph_def, global_step=global_step
      )
  
imports: import threading
  import tensorflow
  from tensorboard.compat.proto import event_pb2
  from tensorboard.compat.proto import graph_pb2
  from tensorboard.compat.proto import meta_graph_pb2
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.util import tb_logging
label_desc: Use image node_id 7 for calling the FileWriter obj's underlying member method code with example usage: obj.add_meta_graph(meta_graph_def, global_step) without return types