about Tick._openNodes about behavior3js

[jcmiao]

i use a map to save current opennodes as bellow:
for i, v := range lastOpenNodes {
if !map.find(key(v)) {
v._close(tick)
}
}

[jcmiao]

It's going to make the node that I opened this time will be closed.
Perhaps because of the parallel node I joined, the tree has multiple running branches, which makes the last time and current opennodes compare