code: function(subtree, method, onComplete) {
              if(method == 'replot') {
                  this.op.sum(subtree, $.extend({ type: 'replot' }, onComplete || {}));
              } else if (method == 'animate') {
                  this.op.sum(subtree, $.extend({ type: 'fade:seq' }, onComplete || {}));
              }
          }
docs: /*
  Method: addSubtree
  
  Adds a subtree.
  
  Parameters:
  subtree - (object) A JSON Tree object. See also <Loader.loadJSON>.
  method - (string) Set this to "animate" if you want to animate the tree after adding the subtree. You can also set this parameter to "replot" to just replot the subtree.
  onComplete - (optional|object) An action to perform after the animation (if any).
  
  Example:
  
  (start code js)
  st.addSubtree(json, 'animate', {
  onComplete: function() {
  alert('complete!');
  }
  });
  (end code)