expand method
Expands this position to an iterable of zero or more positions of using expand.
When expand returns zero or one position it can be considered implementing a filter.
Implementation
PositionSeries expand(ExpandPosition expand) {
final source = positions;
// ignore: avoid_returning_this
if (source.isEmpty) return this;
final target = <Position>[];
for (final pos in source) {
target.addAll(pos.expand(expand));
}
return PositionSeries.from(target);
}