def child(self):
        """
        Return a child of this L{TaskLevel}.

        @return: L{TaskLevel} which is the first child of this one.
        """
        new_level = self._level[:]
        new_level.append(1)
        return TaskLevel(level=new_level)
Return a child of this L{TaskLevel}.

        @return: L{TaskLevel} which is the first child of this one.