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 remove(root, key):
    left, right = split(root, key)
    return merge(left, split(right, key + 1)[1])