DOC: <Issue related to /evaluation/how_to_guides/langgraph>

[userlerueda]

While trying out the example in node_target = example_to_state | app.nodes["agent"]

I get the following error:

    node_target = example_to_state | graph.nodes["classify_node"]
                  ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
  File "/usr/local/lib/python3.11/site-packages/langgraph/pregel/read.py", line 255, in __ror__
    raise NotImplementedError()
NotImplementedError

Any ideas on what could be wrong?

Package versions:

langchain                                0.3.14     Building applications w...
langchain-community                      0.3.14     Community contributed L...
langchain-core                           0.3.29     Building applications w...
langchain-mongodb                        0.2.0      An integration package ...
langchain-openai                         0.2.14     An integration package ...
langchain-text-splitters                 0.3.5      LangChain text splittin...
langgraph                                0.2.61     Building stateful, mult...
langgraph-checkpoint                     2.0.9      Library with base inter...
langgraph-sdk                            0.1.48     SDK for interacting wit...
langsmith                                0.1.147    Client library to conne...