/**
* Returns the number of values associated with the given <code>rowKey</code> between the given
* <code>start</code> and <code>end</code> values.
*/
public int getCount(R rowKey, C start, C end) {
// fetch the relevant pair of trees
final TreePair<C> treePair = getTreePair(rowKey);
// ensure we found something
if (treePair == null) throw new UnknownKeyException("unrecognized rowKey: " + rowKey);
// return the number of values between start and end
return treePair.getCount(start, end);
}
