code: def test_merge_graph_defs_single_graph_def_no_prefix(self):
      graph_def_a = GraphDef()
      text_format.Parse(
          """
                node {
                  name: "A"
                  op: "Input"
                }
                versions {
                  producer: 21
                }
            """,
          graph_def_a,
      )
  
      self.assertProtoEquals(
          graph_def_a,
          graph_util.merge_graph_defs([graph_def_a]),
      )
  
file_path: tensorboard/tensorboard/plugins/graph/graph_util_test.py
imports: from google.protobuf import text_format
  import tensorflow
  from tensorboard.compat.proto.graph_pb2 import GraphDef
  from tensorboard.plugins.graph import graph_util
label_desc: Use image node_id 7 for calling the GraphUtilTest obj's underlying member method code with example usage: obj.test_merge_graph_defs_single_graph_def_no_prefix() without return types