merge method
Merge this label with another one. Merging updates any null attributes of this label with the attributes from lbl
Implementation
void merge(Label lbl) {
for (int i = 0; i < 2; i++) {
if (elt[i] == null && lbl.elt[i] != null) {
elt[i] = new TopologyLocation.fromTL(lbl.elt[i]!);
} else {
elt[i]!.merge(lbl.elt[i]!);
}
}
}