collapsePartialExpansion method
Collapse partial expansion back to fully hidden state.
Clears partialChildIds and partialHyperedgeIds. Returns true if
the node was partially expanded.
Implementation
bool collapsePartialExpansion() {
if (!isPartiallyExpanded) {
return false;
}
partialChildIds = null;
partialHyperedgeIds = null;
return true;
}