The example for the get_children() method contains incorrect argument values
and, if executed, will elicit the following Notice (debug) message:
Notice: Undefined index: children in /home/.../tmp/templates_c/... on line
3...

The example contains this errant line:

     {$cgsimple->get_children('','',$children)}
 
The method itself, however, expects the second argument to be a boolean and the
third argument to be a string containing the name of a variable to assign the
results to.

I propose the following change to the example to correct the problem:
    {$cgsimple->get_children('',false,'children')}