code: def _assert_nodes_are_present(name_to_node, nodes):
      """Assert that nodes are present in the graph."""
      for d in nodes:
          assert d in name_to_node, "%s is not in graph" % d
  
file_path: tensorflow/tensorflow/python/framework/graph_util_impl.py
imports: import copy
  import re
  from tensorflow.core.framework import graph_pb2
  from tensorflow.core.framework import node_def_pb2
  from tensorflow.python.framework import _proto_comparators
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.util import deprecation
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 6 for calling a global function with example usage: _assert_nodes_are_present(name_to_node, nodes) without return types