What does the error message "Python: AttributeError: Can't pickle local object 'writeBuf.<locals>.write'" mean?

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This error message means that an attempt was made to pickle (serialize) a local object named 'writeBuf.<locals>.write', but the object cannot be pickled because it is a local object. It is not possible to serialize a local object because it is bound to the execution context and cannot be transferred to another process or machine.