Objects to be inserted into a tree may not already be parented. Creating cyclic trees is prohibited. Attempt to create invalid heterogeneous tree. All objects in a heterogeneous tree must share a common superclass that is a direct subclass of matlab.mixin.Heterogeneous. The third argument must be either ''first'' or ''last''. The input argument h must be an object that has a parent. CHILDREN may not contain duplicate handles. SIBLINGS may not contain duplicate handles.