def _to_fields(self, data):
        '''
        Return generator over the (numerical) PLY representation of the
        list data (length followed by actual data).
        '''
        (len_t, val_t) = self.list_dtype()

        data = _np.asarray(data, dtype=val_t).ravel()

        yield _np.dtype(len_t).type(data.size)
        for x in data:
            yield x

        Return generator over the (numerical) PLY representation of the
        list data (length followed by actual data).
        
visualizer/plyfile.py