zimbatm's link to http://wiki.ecmascript.org/doku.php?id=harmony:generators http://wiki.ecmascript.org/doku.php?id=harmony:generators was helpful here. https://

zimbatm's link to http://wiki.ecmascript.org/doku.php?id=harmony:generators http://wiki.ecmascript.org/doku.php?id=harmony:generators was helpful here. https://wiki.python.org/moin/Generators https://wiki.python.org/moin/Generators seems to also have some useful background on where the semantics are coming from.