Simplify some code to have one loop, rather than two.

        bits = []

        for node in self:

            if isinstance(node, Node):

                bits.append(self.render_node(node, context))

                bit = self.render_node(node, context)

            else:

                bits.append(node)

        return mark_safe(u''.join([force_unicode(b) for b in bits]))

                bit = node

            bits.append(force_unicode(bit))

        return mark_safe(u''.join(bits))

    def get_nodes_by_type(self, nodetype):

        "Return a list of all nodes of the given type"