getPosition method
Implementation
int getPosition(GroupRef ref) {
if (!_positions.containsKey(ref)) {
var ignoredHint = _previouslyIgnoredRefs.contains(ref) ?
" (It was previously tracked, then later ignored.)" : "";
throw ArgumentError("Position not tracked for ref!$ignoredHint", "ref");
}
ref._positionUsed = true;
return _positions[ref]!;
}