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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def prune_feed_map(meta_graph, feed_map):
 """Function to prune the feedmap of nodes which no longer exist."""

  node_names = [x.name + ":0" for x in meta_graph.graph_def.node]
  keys_to_delete = []
  for k, _ in feed_map.items():
    if k not in node_names:
      keys_to_delete.append(k)
  for k in keys_to_delete:
    del feed_map[k]