//---  public insert ( )-------
template <class Comparable>
void
BST<Comparable>::insert (const Comparable & x)
{
   insert (x, root);
}

// --- private insert ( ) ------
template <class Comparable>
void
BST<Comparable>::
insert (const Comparable & x, BinaryNode * &t )
{
   if (t == NULL)
      t = new BinaryNode<Comparble> (x, NULL, NULL);
   else if (x < t->element)
      insert (x, t->left);
   else if (t->element < x)
      insert (x, t->right);
   else
      ;  // Duplicate, do nothing
}