This is a vendored version of https://github.com/amyangfei/chann/tree/should-consume-data-after-close - that exists here due to an unfixed bug in https://github.com/golang-design/chann/pull/5

gparallel uses a vendored version of chann instaad of a replace directive in the go.mod file, to be able to be installed with a simple go install - which doesn't work if there are any replace directives present.