def adata():
    adata = ad.AnnData(np.zeros((100, 100)))
    adata.obsm["o"] = np.zeros((100, 50))
    adata.varm["o"] = np.zeros((100, 50))
    return adata
def pre_drop(self):
        """
        This is a routine which you could override to backup the tenant schema before dropping.
        :return:
        """