apply method
Implementation
@override
List<DataPoint> apply(
List<DataPoint> input,
DataPointPipelineContext context,
) {
final result = <DataPoint>[];
for (final p in input) {
final base = context.cumulativeByX[p.x] ?? 0.0;
result.add(p.copyWith(y: base));
context.cumulativeByX[p.x] = base + p.dy + context.spacing;
}
return result;
}