How to use the numcodecs.compat.ensure_text function in numcodecs

def decode(self, buf, out=None):
        items = self._decoder.decode(ensure_text(buf, self._text_encoding))
        dec = np.empty(items[-1], dtype=items[-2])
        dec[:] = items[:-2]
        if out is not None:
            np.copyto(out, dec)
            return out
        else:
            return dec

def __init__(self, labels, dtype, astype='u1'):
        self.dtype = np.dtype(dtype)
        if self.dtype.kind not in 'UO':
            raise TypeError("only unicode ('U') and object ('O') dtypes are "
                            "supported")
        self.labels = [ensure_text(label) for label in labels]
        self.astype = np.dtype(astype)
        if self.astype == object:
            raise TypeError('encoding as object array not supported')