finding nodes

        if matches is None:
            matches = []
        parents = self.tree.keys()
        if ttype in self.ttypes and ttype not in matches:
            matches.append(ttype)
        for node in parents:
            if ttype == node:
                #matches.append(node)
                for child in self.tree[node]:
                    self.find_the_node(child, matches)
                    if child not in parents:
                        matches.append(child)
           # else:
           #     for child in self.tree[node]:
           #         if ttype == child and ttype not in matches:
           #             matches.append(child)
        return matches