If a node in the above graph returns { "some_key": "some_string_value" }, this will overwrite the state value for "some_key" with "some_string_value".
However, if multiple nodes in e.g. a fanout within a single step return values for "some_key", the graph will throw this error because
there is uncertainty around how to update the internal state.
To get around this, you can define a reducer that combines multiple values:
importoperatorfromtypingimportAnnotatedclassState(TypedDict):# The operator.add reducer fn makes this append-onlysome_key:Annotated[list,operator.add]
This will allow you to define logic that handles the same key returned from multiple nodes executed in parallel.