+ /**
+ * Inner method to select the sequence numbers for the children of the
+ * current node that intersect the given timestamp. Useful for moving down
+ * the tree.
+ *
+ * @param t
+ * The timestamp to choose which child is the next one
+ * @return Collection of sequence numbers of the child nodes that intersect
+ * t, non-null empty collection if this is a Leaf Node
+ * @throws TimeRangeException
+ * If t is out of the node's range
+ */
+ public abstract @NonNull Collection<@NonNull Integer> selectNextChildren(long t);
+