o new data, the changes to the <code>FFTrees</code> object are not
stored in the input object, unless the (invisible) output of
<code><a href="../reference/plot.FFTrees.html">plot.FFTrees()</a></code> or <code><a href="../reference/print.FFTrees.html">print.FFTrees()</a></code> is
re-assigned to that object. The best way to fit FFTs to training data
and evaluate them to test data is to explicitly include both datasets in
the original <code><a href="../reference/FFTrees.html">FFTrees()</a></code> command by 