* Introduce primitive threading in unified scheduler
* Make the internal struct ExecutedTask not pub
* Improve wording a bit
* Explain scheduler main loop's overhead sensitivity
* Improve wording a bit
* Define ChainedChannel{Sender, Receiver} wrappers
* Clean up a bit
* Use derivative to avoid manual Clone impl
* Clarify comment
* Remove extra whitespace in comment
* Remove unneeded dyn trait for ChainedChannel
* Remove the accumulator thread for now
* Fix typo
* Use unimplemented!() to convey intention better
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