Anytime this comes up I plug the excellent "Unyielding" (https://glyph.twistedmatrix.com/2014/02/unyielding.html https://glyph.twistedmatrix.com/2014/02/unyield

Anytime this comes up I plug the excellent "Unyielding" (https://glyph.twistedmatrix.com/2014/02/unyielding.html https://glyph.twistedmatrix.com/2014/02/unyielding.html) and "Notes on structured concurrency" (https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/ https://vorpus.org/blog/notes-on-structured-concurrency-or-g...) as the counterpoint to "What color is your function". Being able to see structurally what effects your invocation of a function will result in is very helpful in reasoning about the effects of concurrency in a complicated domain.