isAncestorOf static method
Return true if t is u's parent or a node on path to root from u. Use == not equals().
@since 4.5.1
Implementation
static bool isAncestorOf(Tree? t, Tree? u) {
if (t == null || u == null || t.parent == null) return false;
var p = u.parent;
while (p != null) {
if (t == p) return true;
p = p.parent;
}
return false;
}