// here.
			} else if portRemoved(feature) {
				// okay.
			} else if featureSet[featureWithoutContext(feature)] {
				// okay.
			} else {
				fmt.Fprintf(w, "-%s\n", feature)
				ok = false // broke compatibility
			}
		case len(required) == 0 || (len(features) > 0 && required[0] > features[0]):
			newFeature := take(&features)
			fmt.Fprintf(w, "+%s\n", newFeature)
			ok = false // feature not in api/next/*