Compatibility with the Benchmark `Events` API (partially revert f0d91cba2f2017274f5d6ea0419805d651d045f1). Remove `Events#once`.
Compatibility with the Benchmark `Events` API (partially revert f0d91cba2f2017274f5d6ea0419805d651d045f1). Remove `Events#once`.

kitcambridge/spec